Stilbene derivatives, light-emitting element, display device, and electronic device

ABSTRACT

A novel stilbene derivative is provided with motivation of providing a blue emissive material showing excellent color purity. The use of the stilbene derivative of the present invention allows the fabrication of a blue-emissive light-emitting element with excellent color purity. The invention also includes an electronic device equipped with a display portion in which the stilbene derivative is employed. The stilbene derivative of the present invention is represented by formula (1), in which Ar 1  and Ar 2  may form a 5-membered ring by being directly bonded to each other. In formula (1), A 11  represents any one of substituents represented by general formulas (1-1) to (1-3). The variables shown in formula (1) and (1-1) to (1-3) are as defined in the specification.

This application is a divisional of application Ser. No. 13/417,219filed on Mar. 10, 2012 (now U.S. Pat. No. 8,704,215 issued Apr. 22,2014) which is a continuation of application Ser. No. 12/794,893 filedon Jun. 7, 2010 (now U.S. Pat. No. 8,134,148 issued Mar. 13, 2012) whichis a continuation of application Ser. No. 11/860,712 filed on Sep. 25,2007 (now U.S. Pat. No. 7,732,619 issued Jun. 8, 2010). Thisapplication, via its parent application Ser. No. 11/860,712, claimspriority under 35 USC §119 to Japanese Patent Application serial no. JP2006-270118 filed on Sep. 29, 2006 in Japan, which are all incorporatedherein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to stilbene derivatives, light-emittingelements which use stilbene derivatives, display devices having thelight-emitting elements, and electronic devices having the displaydevices. In more detail, the present invention relates to novel stilbenederivatives which can provide excellent color purity of blue; andlight-emitting elements, display devices, and electronic devices whichuse the stilbene derivatives.

2. Description of the Related Art

Light-emitting elements have features such as low-voltage drive, highefficiency, and high luminance and are expected to be applied to flatpanel displays of the next generation. It is considered that alight-emitting device in which light-emitting elements are used for apixel portion is superior to a conventional liquid crystal displaydevice in viewing angle and visibility.

A light-emitting element is formed by interposing a layer including aluminescent substance between a pair of electrodes (an anode and acathode). An emission mechanism thereof is regarded as follows: whenvoltage is applied between the pair of electrodes, holes injected fromthe anode and electrons injected from the cathode recombine in alight-emitting layer including a luminescent substance, whereby amolecular exciton is formed, and energy is released when the molecularexciton relaxes to a ground state. Thus, light is emitted. A luminescentsubstance can exist in singlet excited state and a triplet excitedstate. Light emission from a singlet excited state is referred to asfluorescence and light emission from a triplet excited state is referredto as phosphorescence.

An emission wavelength of a light-emitting element is determined by anenergy difference between a ground state and an excited state, that is,a band gap, of a light-emitting molecule included in the light-emittingelement. Therefore, various emission colors can be obtained by devisinga structure of the light-emitting molecule. By using the light-emittingelements capable of emitting red light, blue light, or green light,which are the three primary colors of light, a full-color light-emittingdevice can be manufactured. Accordingly, highly reliable light-emittingelements which are excellent in color purity and emit red light, bluelight, or green light are being investigated.

As a result of recent development of materials, red emissive and greenemissive light-emitting element with high reliability and excellentcolor purity have been realized. However, a blue emissive light emittingelement having sufficient reliability and color purity has not yet beendeveloped in spite of intensive research thereon (for example, seeReference 1: Japanese Published Patent Application No. 2004-75580).

SUMMARY OF THE INVENTION

In view of the foregoing issues, an object of the present invention isto provide a novel, blue emissive substance which provides excellentcolor purity; and a light-emitting element, a display device, and anelectronic device which use the novel substance.

The present invention provides novel stilbene derivatives. One featureof a stilbene derivative of the present invention includes a structureshown in the following general formula (1).

In the general formula (1), Ar¹ and Ar² each represent an aryl grouphaving 6 to 25 carbon atoms, and the aryl group may include an alkylgroup having 1 to 4 carbon atoms. Further, Ar¹ and Ar² may form a5-membered ring by being directly bonded to each other. A¹¹ representsany one of substituents represented by the general formulas (1-1) to(1-3) below. Further, the bonding positions of nitrogen which includesAr¹ and Ar² and A¹¹ may be any of an ortho position (ortho-substituted),a meta position (meta-substituted), and a para position(para-substituted) with respect to a double bond of stilbene. In otherwords, the diarylamino group (NAr¹Ar²) and A¹¹ can be independentlypara-substituted, meta-substituted, or ortho-substituted on the benzenerings with respect to the double bond (CH═CH).

In the general formulas (1-1) to (1-3), Ar¹¹ to Ar¹³ each represent anaryl group having 6 to 25 carbon atoms; α represents an arylene grouphaving 6 to 25 carbon atoms; Ar²¹ represents an aryl group having 6 to25 carbon atoms; R³¹ represents any one of a hydrogen atom, an alkylgroup having 1 to 4 carbon atoms, and an aryl group having 6 to 25carbon atoms; R³² represents any one of an alkyl group having 1 to 4carbon atoms and an aryl group having 6 to 25 carbon atoms; Ar³¹represents an aryl group having 6 to 25 carbon atoms; β represents anarylene group having 6 to 25 carbon atoms; and R⁴¹ and R⁴² eachrepresent any one of a hydrogen atom, an alkyl group having 1 to 4carbon atoms, and an aryl group having 6 to 25 carbon atoms.

Another feature of a stilbene derivative of the present inventionincludes a structure shown in the following general formula (2).

In the general formula (2), R⁵¹ to R⁶⁰ each represent any one of ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an arylgroup having 6 to 15 carbon atoms. A¹¹ represents any one ofsubstituents represented by the general formulas (1-1) to (1-3) below.The bonding position of a diphenylamino group and A¹¹ may be any of anortho position, a meta position, and a para position with respect to adouble bond of stilbene.

It is to be noted that a stilbene derivative represented by the generalformula (2) is a substance limiting the general formula (1), andcorresponds to a case where Ar¹ and Ar² in general formula (1) eachrepresent an aryl group (for example, a phenyl group) having 6 carbonatoms.

In the general formulas (1-1) to (1-3), Ar¹¹ to Ar¹³ each represent anaryl group having 6 to 25 carbon atoms; α represents an arylene grouphaving 6 to 25 carbon atoms; Ar²¹ represents an aryl group having 6 to25 carbon atoms; R³¹ represents any one of a hydrogen atom, an alkylgroup having 1 to 4 carbon atoms, and an aryl group having 6 to 25carbon atoms; R³² represents any one of an alkyl group having 1 to 4carbon atoms and an aryl group having 6 to 25 carbon atoms; Ar³¹represents an aryl group having 6 to 25 carbon atoms; β represents anarylene group having 6 to 25 carbon atoms; and R⁴¹ and R⁴² eachrepresent any one of a hydrogen atom, an alkyl group having 1 to 4carbon atoms, and an aryl group having 6 to 25 carbon atoms.

Another feature of a stilbene derivative of the present inventionincludes a structure shown in the following general formula (3).

In the general formula (3), R⁶¹ and R⁶² each represent any one of ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an arylgroup having 6 to 25 carbon atoms. A¹¹ represents any one ofsubstituents represented by the general formulas (1-1) to (1-3) below.The bonding positions of an N-carbazolyl group and A¹¹ may be any of anortho position, a meta position, and a para position with respect to adouble bond of stilbene.

It is to be noted that a stilbene derivative represented by the generalformula (3) is a substance limiting a general formula (1), andcorresponds to a case where Ar¹ and Ar² in the general formula (1) eachrepresent an aryl group (for example, a phenyl group) having 6 carbonatoms and Ar¹ and Ar² form a 5-membered ring by being directly bonded toeach other (for example, a carbazole group). In other words, the generalformula (3) corresponds to a case where the diarylamino group (i.e.,NAr¹Ar² unit) in general formula (1) is a carbazole (carbazolyl) group.

In the general formulas (1-1) to (1-3), Ar¹¹ to Ar¹³ each represent anaryl group having 6 to 25 carbon atoms; a represents an arylene grouphaving 6 to 25 carbon atoms; Ar²¹ represents an aryl group having 6 to25 carbon atoms; R³¹ represents any one of a hydrogen atom, an alkylgroup having 1 to 4 carbon atoms, and an aryl group having 6 to 25carbon atoms; R³² represents any one of an alkyl group having 1 to 4carbon atoms and an aryl group having 6 to 25 carbon atoms; Ar³¹represents an aryl group having 6 to 25 carbon atoms; β represents anarylene group having 6 to 25 carbon atoms; and R⁴¹ and R⁴² eachrepresent any one of a hydrogen atom, an alkyl group having 1 to 4carbon atoms, and an aryl group having 6 to 25 carbon atoms.

Another feature of a stilbene derivative of the present inventionincludes a structure shown in the following general formula (4).

In the general formula (4), R⁵¹ to R⁶⁰ each represent any one of ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an arylgroup having 6 to 15 carbon atoms. A¹¹ represents any one ofsubstituents represented by the general formulas (1-1) to (1-3) below.

The general formula (4) is a formula further limiting the generalformula (2) which limits the general formula (1), and the bondingposition of A¹¹ and nitrogen in the general formula (2) is limited inthe general formula (4).

In the general formulas (1-1) to (1-3), Ar¹¹ to Ar¹³ each represent anaryl group having 6 to 25 carbon atoms; α represents an arylene grouphaving 6 to 25 carbon atoms; Ar²¹ represents an aryl group having 6 to25 carbon atoms; R³¹ represents any one of a hydrogen atom, an alkylgroup having 1 to 4 carbon atoms, and an aryl group having 6 to 25carbon atoms; R³² represents any one of an alkyl group having 1 to 4carbon atoms and an aryl group having 6 to 25 carbon atoms; Ar³¹represents an aryl group having 6 to 25 carbon atoms; β represents anarylene group having 6 to 25 carbon atoms; and R⁴¹ and R⁴² eachrepresent any one of a hydrogen atom, an alkyl group having 1 to 4carbon atoms, and an aryl group having 6 to 25 carbon atoms.

Another feature of a stilbene derivative of the present inventionincludes a structure shown in the following general formula (5).

In the general formula (5), R⁶¹ and R⁶² each represent any one of ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an arylgroup having 6 to 25 carbon atoms. A¹¹ represents any one ofsubstituents represented by the general formulas (1-1) to (1-3) below.

The general formula (5) is a formula further limiting the generalformula (3) which limits the general formula (1), and the bondingposition of A¹¹ and nitrogen in the general formula (3) is limited inthe general formula (5).

In the general formulas (1-1) to (1-3), Ar¹¹ to Ar¹³ each represent anaryl group having 6 to 25 carbon atoms; α represents an arylene grouphaving 6 to 25 carbon atoms; Ar²¹ represents an aryl group having 6 to25 carbon atoms; R³¹ represents any one of a hydrogen atom, an alkylgroup having 1 to 4 carbon atoms, and an aryl group having 6 to 25carbon atoms; R³² represents any one of an alkyl group having 1 to 4carbon atoms and an aryl group having 6 to 25 carbon atoms; Ar³¹represents an aryl group having 6 to 25 carbon atoms; β represents anarylene group having 6 to 25 carbon atoms; and R⁴¹ and R⁴² eachrepresent any one of a hydrogen atom, an alkyl group having 1 to 4carbon atoms, and an aryl group having 6 to 25 carbon atoms.

Another feature of a stilbene derivative of the present inventionincludes a structure shown in the following general formula (6).

In the general formula (6), R⁵¹ to R⁶⁰ each represent any one of ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an arylgroup having 6 to 15 carbon atoms. A¹² represents any one ofsubstituents represented by the general formulas (2-1) to (2-3) below.

The general formula (6) is a formula limiting the general formula (1),similarly to the general formula (4). A¹¹ in the general formula (4) isreplaced with A¹² in the general formula (6).

In the general formulas (2-1) to (2-3), Ar¹¹ represents an aryl grouphaving 6 to 25 carbon atoms; R¹¹ to R²⁴ each represent any one of ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an arylgroup having 6 to 15 carbon atoms; Ar²¹ represents an aryl group having6 to 25 carbon atoms; R³¹ represents any one of a hydrogen atom, analkyl group having 1 to 4 carbon atoms, and an aryl group having 6 to 25carbon atoms; R³³ to R³⁷ each represent any one of a hydrogen atom, analkyl group having 1 to 4 carbon atoms, and an aryl group having 6 to 15carbon atoms; Ar³¹ represents an aryl group having 6 to 25 carbon atoms;R⁴¹ and R⁴² each represent any one of a hydrogen atom, an alkyl grouphaving 1 to 4 carbon atoms, and an aryl group having 6 to 25 carbonatoms; and R⁴³ to R⁴⁶ each represent any one of a hydrogen atom, analkyl group having 1 to 4 carbon atoms, and an aryl group having 6 to 15carbon atoms.

Another feature of a stilbene derivative of the present inventionincludes a structure shown in the following general formula (7).

In the general formula (7), R⁶¹ and R⁶² each represent any one of ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an arylgroup having 6 to 25 carbon atoms. A¹² represents any one ofsubstituents represented by the general formulas (2-1) to (2-3) below.

The general formula (7) is a formula limiting the general formula (1),similarly to the general formula (5). A¹¹ in the general formula (5) isreplaced with A¹² in the general formula (7).

In the general formulas (2-1) to (2-3), Ar¹¹ represents an aryl grouphaving 6 to 25 carbon atoms; R¹¹ to R²⁴ each represent any one of ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an arylgroup having 6 to 15 carbon atoms; Ar²¹ represents an aryl group having6 to 25 carbon atoms; R³¹ represents any one of a hydrogen atom, analkyl group having 1 to 4 carbon atoms, and an aryl group having 6 to 25carbon atoms; R³³ to R³⁷ each represent any one of a hydrogen atom, analkyl group having 1 to 4 carbon atoms, and an aryl group having 6 to 15carbon atoms; Ar³¹ represents an aryl group having 6 to 25 carbon atoms;R⁴¹ and R⁴² each represent any one of a hydrogen atom, an alkyl grouphaving 1 to 4 carbon atoms, and an aryl group having 6 to 25 carbonatoms; and R⁴³ to R⁴⁶ each represent any one of a hydrogen atom, analkyl group having 1 to 4 carbon atoms, and an aryl group having 6 to 15carbon atoms.

Another feature of a stilbene derivative of the present inventionincludes a structure shown in the following general formula (8).

In the general formula (8), R⁵¹ and R⁶⁰ each represent any one of ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an arylgroup having 6 to 15 carbon atoms. A¹³ represents any one ofsubstituents represented by the following general formulas (3-1) to(3-3).

In the general formulas (3-1) to (3-3), Ar¹¹ represents an aryl grouphaving 6 to 25 carbon atoms; R²⁵ and R²⁶ each represent any one of ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an arylgroup having 6 to 15 carbon atoms; Ar²¹ represents an aryl group having6 to 25 carbon atoms; R³¹ represents any one of a hydrogen atom, analkyl group having 1 to 4 carbon atoms, and an aryl group having 6 to 25carbon atoms; Ar³¹ represents an aryl group having 6 to 25 carbon atoms;and R⁴¹ and R⁴² each represent any one of a hydrogen atom, an alkylgroup having 1 to 4 carbon atoms, and an aryl group having 6 to 25carbon atoms.

Another feature of a stilbene derivative of the present inventionincludes a structure shown in the following general formula (9).

In the general formula (9), R⁶¹ and R⁶² each represent any one of ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an arylgroup having 6 to 25 carbon atoms. A¹³ represents any one ofsubstituents represented by the following general formulas (3-1) to(3-3).

In the general formulas (3-1) to (3-3), Ar¹¹ represents an aryl grouphaving 6 to 25 carbon atoms; R²⁵ and R²⁶ each represent any one of ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an arylgroup having 6 to 15 carbon atoms; Ar²¹ represents an aryl group having6 to 25 carbon atoms; R³¹ represents any one of a hydrogen atom, analkyl group having 1 to 4 carbon atoms, and an aryl group having 6 to 25carbon atoms; Ar³¹ represents an aryl group having 6 to 25 carbon atoms;and R⁴¹ and R⁴² each represent any one of a hydrogen atom, an alkylgroup having 1 to 4 carbon atoms, and an aryl group having 6 to 25carbon atoms.

One feature of a light-emitting element of the present invention is tohave the stilbene derivative according to any one of the generalformulas (1) to (9) for a light-emitting layer between a pair ofelectrodes.

Another feature of a light-emitting element of the present invention isto have the stilbene derivative according to any one of the generalformulas (1) to (9) for a part of a light-emitting layer between a pairof electrodes.

One feature of a display device of the present invention is to have theabove-mentioned light-emitting element in a pixel portion.

One feature of an electronic device of the present invention is that thedisplay device mentioned above is used for a display portion.

By using a novel stilbene derivative of the present invention,blue-emissive light-emitting element with excellent color purity can beprovided. Further, by using the light-emitting element of the presentinvention for the display portion, a display device and an electronicdevice which are excellent in color reproducibility can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 shows a light-emitting element of the present invention;

FIG. 2 shows an element substrate having a light-emitting element of thepresent invention;

FIGS. 3A and 3B each show an element substrate having a light-emittingelement of the present invention;

FIGS. 4A and 4B show a light-emitting device having a light-emittingelement of the present invention;

FIGS. 5A to 5C each show an electronic device of the present invention;

FIGS. 6A and 6B each show a ¹H NMR chart of(E)-4-{N-[4-(9H-carbazol-9-yl)phenyl]-N-phenyl}amino-4′-(9H-carbazol-9-yl)stilbene(abbreviation: YGACzS);

FIGS. 7A and 7B each show an absorption spectrum of YGACzS;

FIGS. 8A and 8B each show an emission spectrum of YGACzS;

FIGS. 9A and 9B each show a result of CV measurement of YGACzS;

FIGS. 10A and 10B each show a ¹H NMR chart of(E)-4-{N-[4-(9H-carbazol-9-yl)phenyl]-N-phenyl}amino-4′-diphenylaminostilbene(Abbreviation: YGADPhAS);

FIGS. 11A and 11B each show an absorption spectrum of YGADPhAS;

FIGS. 12A and 12B each show an emission spectrum of YGADPhAS;

FIGS. 13A and 13B each show a result of CV measurement of YGADPhAS;

FIG. 14 shows element characteristics of a light-emitting elementmanufactured using YGACzS;

FIG. 15 shows element characteristics of a light-emitting elementmanufactured using YGACzS;

FIG. 16 shows element characteristics of a light-emitting elementmanufactured using YGACzS;

FIG. 17 shows an emission spectrum of a light-emitting elementmanufactured using YGACzS;

FIG. 18 shows element characteristics of a light-emitting elementmanufactured using YGACzS;

FIG. 19 shows element characteristics of a light-emitting elementmanufactured using YGACzS;

FIG. 20 shows element characteristics of a light-emitting elementmanufactured using YGACzS;

FIG. 21 shows element characteristics of a light-emitting elementmanufactured using YGACzS;

FIG. 22 shows element characteristics of a light-emitting elementmanufactured using YGADPhAS;

FIG. 23 shows element characteristics of a light-emitting elementmanufactured using YGADPhAS;

FIG. 24 shows element characteristics of a light-emitting elementmanufactured using YGADPhAS;

FIG. 25 shows an emission spectrum of a light-emitting elementmanufactured using YGADPhAS;

FIGS. 26A and 26B each show a ¹H NMR chart ofN-{4-[(E)-4-(9H-carbazol-9-yl)styryl]phenyl}-N,9-diphenyl-9H-carbazol-3-amine(Abbreviation: PCACzS);

FIG. 27 shows an absorption spectrum of PCACzS;

FIG. 28 shows an emission spectrum of PCACzS;

FIGS. 29A and 29B each show a ¹H NMR chart ofN-{4-[(E)-4-(diphenylamino)styryl]phenyl}-N,N′,N′-triphenyl-1,4-phenylenediamine(Abbreviation: DPAPhAS);

FIG. 30 shows an absorption spectrum of DPAPhAS; and

FIG. 31 shows an emission spectrum of DPAPhAS.

DETAILED DESCRIPTION OF THE INVENTION

Embodiment Modes of the present invention will be described below withreference to the accompanying drawings. However, the present inventionis not limited to the description given below, and it will be readilyapparent to those skilled in the art that various changes andmodifications in modes and details thereof can be made without departingfrom the purpose and scope of the present invention. Therefore, thepresent invention should not be interpreted as being limited to thedescription of the embodiment modes given below. It is to be noted thatin embodiments of the present invention which are described below, likereference numerals are used for like portions throughout the drawingsand chemical formulas.

Embodiment Mode 1

One feature of a stilbene derivative of the present invention includes astructure represented by the following general formula (1).

In the general formula (1), Ar¹ and Ar² each represent an aryl grouphaving 6 to 25 carbon atoms, and the aryl group may include an alkylgroup having 1 to 4 carbon atoms. Ar¹ and Ar² may form a 5-membered ringby being directly bonded to each other. That is, the general formula (2)below shows one mode of a case where Ar¹ and Ar² are not directly bondedto each other, and the general formula (3) below shows one mode of acase where Ar¹ and Ar² form a 5-membered ring (for example, a carbazolegroup) by being directly bonded to each other.

It is to be noted that “carbon atoms” in “an aryl group having 6 to 25carbon atoms” relating to “Ar¹ and Ar²” and the like in the generalformula (1) are carbon atoms which form an aromatic ring, and carbonatoms of a substituent bonded to the aromatic ring are not includedtherein. That is, “an aryl group having 6 to 25 carbon atoms” whichcorresponds to “Ar¹ and Ar²” and the like is exemplified in the formulas(21-1) to (21-9) below, and, for example, the formula (21-1) representsan aryl group having 6 carbon atoms, and the formula (21-5) representsan aryl group having 10 carbon atoms. The formula (21-7) having twomethyl groups and a methylene group bonded to the two methyl groups assubstituents represents an aryl group having 12 carbon atoms, andcarbons of the two methyl groups and the methylene group bonded to thetwo methyl groups are not included in carbons of the aryl group.

In the general formula (2), R⁵¹ to R⁶⁰ each represent any one of ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an arylgroup having 6 to 15 carbon atoms. In the general formula (3), R⁶¹ andR⁶² each represent any one of a hydrogen atom, an alkyl group having 1to 4 carbon atoms, and an aryl group having 6 to 25 carbon atoms.

In each of the general formulas (1) to (3), A¹¹ represents any one ofsubstituents represented by the following general formulas (1-1) to(1-3).

In the general formulas (1-1) to (1-3), Ar¹¹ to Ar¹³ each represent anaryl group having 6 to 25 carbon atoms; α represents an arylene grouphaving 6 to 25 carbon atoms; Ar²¹ represents an aryl group having 6 to25 carbon atoms; R³¹ represents any one of a hydrogen atom, an alkylgroup having 1 to 4 carbon atoms, and an aryl group having 6 to 25carbon atoms; R³² represents any one of an alkyl group having 1 to 4carbon atoms and an aryl group having 6 to 25 carbon atoms; Ar³¹represents an aryl group having 6 to 25 carbon atoms; β represents anarylene group having 6 to 25 carbon atoms; and R⁴¹ and R⁴² eachrepresent any one of a hydrogen atom, an alkyl group having 1 to 4carbon atoms, and an aryl group having 6 to 25 carbon atoms.

It is to be noted that, as explained above, carbon atoms of the arylenegroup are the same as in the case of the aryl group.

The bonding position of A¹¹ may be any of an ortho position, a metaposition, and a para position with respect to the double bond ofstilbene. For example, a case where a bonding position of A¹¹ is a paraposition with respect to the double bond of stilbene in general formulas(2) and (3) is represented by general formulas (4) and (5) below. Alight-emitting element in which a stilbene derivative having A¹¹ at apara position with respect to the double bond of stilbene, as shown ingeneral formulas (4) and (5), is used for a light-emitting layer or apart of a light-emitting layer has high quantum efficiency. Therefore, alight-emitting element which uses a stilbene derivative having A¹¹ at apara position is preferable since the light-emitting element can bedriven at lower current density compared with a case where A¹¹ is bondedat an ortho position or a meta position.

As modes of general formulas (1-1) to (1-3), the general formulas (2-1)to (2-3) are respectively given. In the general formulas (2-1) to (2-3),Ar¹¹ represents an aryl group having 6 to 25 carbon atoms; R¹¹ to R²⁴each represent any one of a hydrogen atom, an alkyl group having 1 to 4carbon atoms, and an aryl group having 6 to 15 carbon atoms; Ar²¹represents an aryl group having 6 to 25 carbon atoms; R³¹ represents anyone of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, andan aryl group having 6 to 25 carbon atoms; R³³ to R³⁷ each represent anyone of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, andan aryl group having 6 to 15 carbon atoms; Ar³¹ represents an aryl grouphaving 6 to 25 carbon atoms; R⁴¹ and R⁴² each represent any one of ahydrogen atom, an alkyl group having 1 to 4 carbon atoms, and an arylgroup having 6 to 25 carbon atoms; and R⁴³ to R⁴⁶ each represent any oneof a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, and anaryl group having 6 to 15 carbon atoms.

The general formulas (3-1) to (3-3) below can be given as modes limitinggeneral formulas (1-1) to (1-3), respectively. In the general formulas(3-1) to (3-3), Ar¹¹ represents an aryl group having 6 to 25 carbonatoms; R²⁵ and R²⁶ each represent any one of a hydrogen atom, an alkylgroup having 1 to 4 carbon atoms, and an aryl group having 6 to 15carbon atoms; A²¹ represents an aryl group having 6 to 25 carbon atoms;R³¹ represents any one of a hydrogen atom, an alkyl group having 1 to 4carbon atoms, and an aryl group having 6 to 25 carbon atoms; Ar³¹represents an aryl group having 6 to 25 carbon atoms; and R⁴¹ and R⁴²each represent any one of a hydrogen atom, an alkyl group having 1 to 4carbon atoms, and an aryl group having 6 to 25 carbon atoms.

As specific modes of Ar¹¹ to Ar¹³ in the general formula (1-1), thefollowing formulas (21-1) to (21-9) can be given.

As specific modes of α in the general formula (1-1), the followingformulas (22-1) to (22-9) can be given.

As specific examples of the general formula (1-1), the followingformulas (31-1) to (31-23) can be given.

As specific modes of Ar²¹ in the general formula (1-2), the followingformulas (23-1) to (23-9) can be given.

As specific modes of R³¹ in the general formula (1-2), the followingformulas (24-1) to (24-18) can be given.

As specific modes of R³² in the general formula (1-2), the followingformulas (25-1) to (25-17) can be given.

As specific examples of the general formula (1-2), the followingformulas (32-1) to (32-42) can be given.

As specific modes of A³¹ in the general formula (1-3), the followingformulas (26-1) to (26-9) can be given.

As specific modes of β in the general formula (1-3), the followingformulas (27-1) to (27-9) can be given.

As specific modes of R⁴¹ and R⁴² in the general formula (1-3), thefollowing formulas (28-1) to (28-18) can be respectively given.

As specific examples of the general formula (1-3), the followingformulas (33-1) to (33-34) can be given.

Embodiment Mode 2

In this embodiment mode, an example of a synthetic method of a stilbenederivative, in which A¹¹ represents a substituent represented by ageneral formula (1-1) in the general formula (1) described in EmbodimentMode 1, is described. That is, an example of a synthetic method of astilbene derivative represented by a general formula (1-1-1) below isdescribed. In the general formula (1-1-1), Ar¹ and Ar² may form a5-membered ring by being directly bonded to each other. α in the generalformula (1-1-1) represents an arylene group having 6 to 25 carbon atoms.

Step 1; Synthesis of a Stilbene Derivative (St1) in which any One of2-Position to 4-Position is Halogenated

First, as represented by the following synthetic scheme (A-1), byreacting benzyltriphenylphosphonium salt (α1) in which any one of2-position to 4-position is halogenated, with a benzaldehyde derivative(β1) in the presence of a base, in other words by a so-called Wittigreaction, a stilbene derivative (St1) in which any one of 2-position to4-position is halogenated is obtained. X¹ and X² in the synthetic scheme(A-1) each represent halogen, preferably bromine or iodine.

Further, this stilbene derivative (St1) can also be obtained by aHorner-Emmons reaction in which phosphonate ester (α2) is used insteadof the triphenylphosphonium salt (α1), as shown in a synthetic scheme(A-1′). R¹ in the synthetic scheme (A-1′) represents an alkyl group. Asthe base, organic bases such as metal alkoxide can be used.

In addition, the stilbene derivative (St1) can also be obtained by theWittig reaction as shown in a synthesis scheme (A-1″). Namely,benzyltriphenylphosphonium salt (α3) in which any one of 2-position to4-position is substituted by a diarylamino group having Ar¹ and Ar² andbenzaldehyde (β2) in which any one of 2-position to 4-position ishalogenated are reacted in the presence of a base. Alternatively, asshown by a synthetic scheme (A-1′″), it can also be obtained by aHorner-Emmons reaction in which phosphonate ester (α4) is used insteadof the triphenylphosphonium salt (α3).

Step 2; Synthesis of a Diamine Derivative (γ2)

Next, as shown by a synthetic scheme (A-2) below, a diamine derivative(γ2) is obtained by coupling a monohalogenated triarylamine (γ1) andarylamine using a metal or a metal compound in the presence of a base.X³ in the synthetic scheme (A-2) represents halogen, preferably bromineor iodine. As a specific example of a metal compound for the coupling,monovalent copper such as copper(I) iodide can be given.

As a specific example of a metal compound used as a catalyst in thecoupling, a palladium catalyst such as palladium(II) acetate,tetrakis(triphenylphosphine)palladium(0), orbis(dibenzylideneacetone)palladium(0) can be given. As the base,inorganic bases such as potassium carbonate or sodium carbonate ororganic bases such as metal alkoxide (for example, sodium tert-butoxideor potassium tert-butoxide) can be used.

Step 3; Synthesis of a Stilbene Derivative of the Present InventionRepresented by the General Formula (1)

Next, as shown by a synthesis scheme (A-3) below, a stilbene derivativeof the present invention represented by the general formula (1-1-1) canbe obtained by coupling the stilbene derivative (St1) obtained in Step 1and the diamine derivative (γ2) obtained in Step 2 using a metal or ametal compound in the presence of a base. As the metal and the metalcompound, any of the above-described substances can be used. As thebase, inorganic bases such as potassium carbonate or sodium carbonate ororganic bases such as metal alkoxide (for example, sodium tert-butoxideor potassium tert-butoxide) can be used.

Embodiment Mode 3

In this embodiment mode, an example of a synthetic method of a stilbenederivative in a case where A¹¹ represents a substituent represented by ageneral formula (1-2) in the general formula (1) described in EmbodimentMode 1, is described. That is, an example of a synthetic method of astilbene derivative represented by the following general formula (1-1-2)is described. In the general formula (1-1-2), Ar¹ and Ar² may form a5-membered ring by being directly bonded to each other.

Step 1; Synthesis of a Stilbene Derivative (St1) in which any One of2-Position to 4-Position is Halogenated

A stilbene derivative (St1) can be synthesized using the syntheticschemes (A-1) to (A-1′″) described in Step 1 of Embodiment Mode 2;therefore, the description of the synthesis is omitted here.

Step 2; Synthesis of a carbazol-3-amine Derivative (Cz1)

Next, as shown by a synthetic scheme (B-2) below, a carbazol-3-aminederivative (Cz1) is obtained by coupling a carbazole derivative (γ3) inwhich one of the 3-positions is halogenated and arylamine using a metalor a metal compound in the presence of a base. X⁴ in the syntheticscheme (B-2) represents halogen, preferably bromine or iodine. As themetal or the metal compound for the coupling, the above-describedsubstances can be used. As the base, inorganic bases such as potassiumcarbonate or sodium carbonate or organic bases such as metal alkoxide(for example, sodium tert-butoxide or potassium tert-butoxide) can beused.

Step 3; Synthesis of a Stilbene Derivative of the Present InventionRepresented by the General Formula (1)

Next, as shown by the following synthesis scheme (B-3), a stilbenederivative of the present invention represented by the general formula(1-1-2) can be obtained by coupling the stilbene derivative (St1)obtained in Step 1 and the carbazole-3-amine derivative (Cz1) obtainedin Step 2 using a metal or a metal compound in the presence of a base.As the metal or the metal compound, the above-described substances canbe used. As the base, inorganic bases such as potassium carbonate orsodium carbonate or organic bases such as metal alkoxide (for example,sodium tert-butoxide or potassium tert-butoxide) can be used.

Embodiment Mode 4

In this embodiment mode, an example of a synthetic method of a stilbenederivative in a case where A¹¹ represents a substituent represented by ageneral formula (1-3) in the general formula (1), is described. That is,an example of a synthetic method of a stilbene derivative represented bythe following general formula (1-1-3) is described. In the generalformula (1-1-3), Ar¹ and Ar² may form a 5-membered ring by beingdirectly bonded to each other.

Step 1; Synthesis of a Stilbene Derivative (St1) in which any One of2-Position to 4-Position is Halogenated

A stilbene derivative (St1) can be synthesized using the syntheticschemes (A-1) to (A-1′″) described in Step 1 of Embodiment Mode 2;therefore, the description of the synthesis is omitted here.

Step 2; Synthesis of a Diarylamine Derivative (Cz2) Having Carbazole

Next, as shown by a synthetic scheme (C-2) below, a diarylaminederivative (Cz2) having carbazole is obtained by coupling a9-arylcarbazole derivative (γ4) in which a halogen atom is introduced tothe aryl group and arylamine using a metal or a metal compound in thepresence of a base. X⁵ and X⁶ in the synthetic scheme (C-2) eachrepresent halogen, preferably bromine or iodine.

β in the synthetic scheme (A-1) represents an arylene group having 6 to25 carbon atoms. As the metal or the metal compound, used at thecoupling, the above-described substances can be used. As the base,inorganic bases such as potassium carbonate or sodium carbonate ororganic bases such as metal alkoxide (for example, sodium tert-butoxideor potassium tert-butoxide) can be used.

Step 3; Synthesis of a Stilbene Derivative of the Present InventionRepresented by the General Formula (1)

Next, as shown by a synthesis scheme (C-3) below, a stilbene derivativeof the present invention represented by the general formula (1-1-3) canbe obtained by coupling the stilbene derivative (St1) obtained in Step 1and the diarylamine derivative (Cz2) having carbazole obtained in Step 2using a metal or a metal compound in the presence of a base. As themetal or the metal compound, the above-described substances can be used.As the base, inorganic bases such as potassium carbonate or sodiumcarbonate or organic bases such as metal alkoxide (for example, sodiumtert-butoxide or potassium tert-butoxide) can be used.

Embodiment Mode 5

In this embodiment mode, an example of a light-emitting element whichuses a stilbene derivative described in Embodiment Mode 1 for alight-emitting layer or a part of a light-emitting layer, and a methodfor manufacturing the same is described.

An element structure of a light-emitting element of the presentinvention has a structure in which a layer 103 including a luminescentsubstance is interposed between a first electrode 101 and a secondelectrode 102 as shown in FIG. 1.

A stilbene derivative of the present invention is used for the layer 103including a luminescent substance. In this embodiment mode, a case isdescribed in which the first electrode serves as an anode and the secondelectrode serves as a cathode. However, in a structure of alight-emitting element of the present invention, the first electrode canalso serve as a cathode and the second electrode can serve as an anode.The anode is an electrode which injects holes into the layer including aluminescent substance and the cathode is an electrode which injectselectrons into the layer including a luminescent substance.

The layer 103 including a luminescent substance includes at least alight-emitting layer 104. As examples of the structure of the layer 103including a luminescent substance, a stacked structure including a holeinjecting layer, a light-emitting layer, and an electron transportinglayer in that order, a stacked structure including a hole injectinglayer, a hole transporting layer, a light-emitting layer, and anelectron transporting layer in that order; a stacked structure includinga hole injecting layer, a hole transporting layer, a light-emittinglayer, a hole blocking layer, and an electron transporting layer in thatorder; a stacked structure including a hole injecting layer, a holetransporting layer, a light-emitting layer, a hole blocking layer, anelectron transporting layer, and an electron injecting layer in thatorder, and the like can be given.

A stilbene derivative of the present invention is preferably used forthe light-emitting layer 104. That is, it is preferable to employ astructure using a stilbene derivative of the present invention for thelight-emitting layer 104 or a structure using a stilbene derivative ofthe present invention as a dopant (light-emitting material) for a partof the light-emitting layer 104.

Further, the light-emitting element of the present invention ispreferably supported over a substrate. There is no particular limitationon the kind of the substrate, and a glass substrate, a quartz substrate,a silicon substrate, a metal substrate (for example, a stainless steelsubstrate), a ceramic substrate, a plastic substrate (for example, anacrylic substrate), or the like can be used.

As for an anode material for the light-emitting element, use of a metal,an alloy, a conductive compound having a high work function (a workfunction of 4.0 eV or more), a mixture thereof, or the like ispreferred. Specific examples of the anode material include gold (Au),platinum (Pt), titanium (Ti), nickel (Ni), tungsten (W), chromium (Cr),molybdenum (Mo), iron (Fe), cobalt (Co), copper (Cu), palladium (Pd), anitride of a metal material (for example, titanium nitride), or thelike, in addition to ITO (indium tin oxide), and IZO (indium zinc oxide)which includes silicon oxide and 2 to 20 atomic % of zinc oxide inindium oxide.

In a case where a first buffer layer described below is provided incontact with the anode on the light-emission layer side of the anode, anohmic contact is realized between the buffer layer and the anode, whichallows the use of a variety of electrode material as an anode regardlesswork function thereof. Thus, aluminum (Al), silver (Ag), an alkalimetal, an alkaline-earth metal such as magnesium (Mg), an alloyincluding these (e.g., Mg:Ag, Al:Li), or the like which are commonlyknown as materials having a low work function, can be used as the anodematerial.

The first buffer layer is formed by combining a metal compound and anorganic compound such as an aromatic amine compound, a carbazolederivative, or an aromatic hydrocarbon (including an aromatichydrocarbon having at least one vinyl skeleton).

As the aromatic amine compound, for example,4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB);4,4′-bis[N-(3-methylphenyl)-N-phenylamino]biphenyl (abbreviation: TPD);4,4′,4″-tris(N,N-diphenylamino)triphenylamine (abbreviation: TDATA);4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine(abbreviation: MTDATA); and the like can be given as specific examples.

Further,4,4′-bis(N-{4-[N,N-bis(3-methylphenyl)amino]phenyl}-N-phenylamino)biphenyl(abbreviation: DNTPD); 1,3,5-tris[N,N-di(m-tolyl)amino]benzene(abbreviation: m-MTDAB); 4,4′,4″-tri(N-carbazolyl)triphenylamine(abbreviation: TCTA); 2,3-bis(4-diphenylaminophenyl) quinoxaline(abbreviation: TPAQn);2,2′,3,3′-tetrakis(4-diphenylaminophenyl)-6,6′-bisquinoxaline(abbreviation: D-TriPhAQn);2,3-bis{4-[N-(1-naphthyl)-N-phenylamino]phenyl}dibenzo[fh]quinoxaline(abbreviation: NPADiBzQn); and the like can be given as specificexamples.

As the carbazole derivative, for example,3-[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA1);3,6-bis[N-(9-phenylcarbazol-3-yl)-N-phenylamino]-9-phenylcarbazole(abbreviation: PCzPCA2); N-(2-naphthyl)carbazole (abbreviation: NCz);4,4′-di(N-carbazolyl)biphenyl (abbreviation: CBP);9,10-bis[4-(N-carbazolyl)phenyl]anthracene (abbreviation: BCPA);3,5-bis[4-(N-carbazolyl)phenyl]biphenyl (abbreviation: BCPBi);1,3,5-tris[4-(N-carbazolyl)phenyl]benzene (abbreviation: TCPB) and thelike can be given as specific examples.

As the aromatic hydrocarbon (including an aromatic hydrocarbon having atleast one vinyl skeleton), anthracene, 9,10-diphenylanthracene(abbreviation: DPAnth.); 2-tert-butyl-9,10-di(2-naphthyl)anthracene(abbreviation: t-BuDNA); tetracene; rubrene; pentacene;4,4′-bis(2,2-diphenylvinyl)biphenyl (abbreviation: DPVBi); and the likecan be given as specific examples.

As the metal compound, an oxide or nitride of a transition metal ispreferable. In particular, an oxide or nitride of a metal which belongsto Group 4 to 8 is preferable. In addition, a material having anelectron-accepting property with respect to the above-described aromaticamine compounds, carbazole derivatives, and aromatic hydrocarbons(including aromatic hydrocarbons having at least one vinyl skeleton) ispreferable. As such a metal compound, for example, molybdenum oxide,vanadium oxide, ruthenium oxide, rhenium oxide, titanium oxide, chromiumoxide, zirconium oxide, hafnium oxide, tantalum oxide, tungsten oxide,silver oxide, and the like can be given as specific examples.

Even when any of an aromatic amine, a carbazole derivative, or anaromatic hydrocarbon (including an aromatic hydrocarbon having at leastone vinyl skeleton) is used as the organic compound in the first bufferlayer, it is preferable that a weight ratio of the metal compound to theorganic compound is 0.5 to 2, or a molar ratio is 1 to 4. In addition,the first buffer layer may have a thickness greater than or equal to 50nm, because it has high conductivity.

As for a cathode material of the light-emitting element, use of a metal,an alloy, a conductive compound having a low work function (a workfunction of 3.8 eV or less), a mixture thereof, or the like ispreferred. As specific examples of the cathode material, an elementbelonging to Group 1 or 2 of the periodic table, that is, an alkalimetal such as Li or Cs, an alkaline earth metal such as Mg, Ca, or Sr,and the like can be given. As other examples of the cathode material, analloy (e.g., Mg:Ag, Al:Li) or a metal compound (e.g., LiF, CsF, or CaF₂)which include an alkali metal or an alkaline earth metal can be used,and a transition metal which includes a rare earth metal can also beused. Further, a structure obtained by stacking metals such as Al, Ag,and ITO (indium tin oxide) or an alloy can also be used.

In a case where a second buffer layer described below is provided incontact with the cathode on a light-emitting layer side of the cathode,an ohmic contact of the buffer layer with an electrode material having awide range of work function is possible. Thus, ITO, indium tin oxideincluding silicon oxide, IZO (indium zinc oxide) which includes siliconoxide and 2 to 20 atomic % of zinc oxide in indium oxide, and the like,which are commonly known as materials with a high work function, can beused as the cathode material.

The second buffer layer is formed by a combination of at least onesubstance selected from electron transporting substances and bipolarsubstances, and a substance (a donor) showing an electron-donatingproperty with respect to these substances. As examples of the substance(the donor) showing an electron-donating property, alkali metal such asLi or Cs and an alkaline earth metal such as Mg or Ca can be given. Asthe electron transporting substance and the bipolar substance, asubstance having an electron mobility of 1×10⁻⁶ cm²/Vs or more ispreferable. In addition, substances to be described below can be usedfor each of the electron transporting substance and the bipolarsubstance.

Formation of a thin film from the anode material and the cathodematerial described above using an evaporation method, a sputteringmethod, or the like allows the fabrication of an anode and a cathode,respectively. The anode and the cathode each preferably have a thicknessof 10 to 500 nm.

The light-emitting element of the present invention has a structure inwhich light generated by recombination of carriers (hole and electron)in the layer including a luminescent substance is emitted outsidethrough one or both of the anode and the cathode. In other words, theanode is made of a material having a light transmitting property in acase where light is extracted through the anode, and the cathode is madeof a material having a light transmitting property in a case where lightis extracted through the cathode side.

For the layer including a luminescent substance, known materials can beused, and either compounds with low molecular weight or high molecularweight can be used. The materials for forming the layer including aluminescent substance may include not only an organic compound but alsoan inorganic compound.

The layer including a luminescent substance is formed by appropriatelycombining layers such as the first buffer layer and the second bufferlayer described above as well as a hole injecting layer including a holeinjecting substance, a hole transporting layer including a holetransporting substance or a bipolar substance, a light-emitting layerincluding a luminescent substance, a hole blocking layer including ahole blocking substance, an electron transporting layer including anelectron transporting substance, and an electron injecting layerincluding an electron injecting substance.

In the present invention, in the case of using the stilbene derivativefor the light-emitting layer, the layer including a luminescentsubstance interposed between a pair of electrodes can be formed bystacking the light-emitting layer and other layers (for example, thehole injecting layer, the hole transporting layer, the hole blockinglayer, the electron transporting layer, the electron injecting layer,the first buffer layer, the second buffer layer, or the like). Specificsubstances used for forming these layers are described below.Description of the first buffer layer and the second buffer layer isomitted here, because it has already been made.

The hole injecting layer is preferably formed using a hole injectingsubstance. As the hole injecting substance, porphyrin- andphthalocyanine-based compounds are efficient among organic compounds.For example, phthalocyanine (hereinafter, referred to as “H₂-Pc”),copper phthalocyanine (hereinafter, referred to as “Cu-Pc”), or the likecan be used. In addition, a chemically doped conductive compound withhigh molecular weight such as poly(3,4-ethylenedioxythiophene)(hereinafter, referred to as “PEDOT”) doped with poly(styrenesulfonicacid) (hereinafter, referred to as “PSS”) can be used.

The hole transporting layer is a layer excellent in a hole transportingproperty, and is preferably formed of a hole transporting substance or abipolar substance which has a hole mobility of 1×10⁻⁶ cm²/Vs or more.The hole transporting substance is a substance having higher holemobility than electron mobility, and is preferably a substance having avalue of a ratio of hole mobility to electron mobility (=holemobility/electron mobility) of more than 100.

As the hole transporting substance, for example, an aromatic amine-based(namely a substance having a bond of benzene ring-nitrogen) compound ispreferable. As specific examples of a substance which is widely used,for example, 4,4′-bis[N-(3-methylphenyl)-N-phenylamino]biphenyl(hereinafter, referred to as “TPD”);4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (hereinafter, referred toas “NPB”) which is a derivative thereof; a star burst aromatic aminecompound such as 4,4′,4″-tri(N-carbazolyl)triphenylamine (hereinafter,referred to as “TCTA”), 4,4′,4″-tris(N,N-diphenylamino)triphenylamine(hereinafter, referred to as “TDATA”), or4,4′,4″-tris[N-(3-methylphenyl)-N-phenylamino]triphenylamine(hereinafter, referred to as MTDATA) can be given.

The bipolar substance is a substance which is described as follows: whenmobility of an electron and mobility of a hole are compared with eachother, a value of a ratio of mobility of one carrier to mobility of theother carrier is less than or equal to 100, preferably less than orequal to 10. As the bipolar substance, for example,2,3-bis(4-diphenylaminophenyl) quinoxaline (abbreviation: TPAQn);2,3-bis{4-[N-(1-naphthyl)-N-phenylamino]phenyl}dibenzo[f,h]quinoxaline(abbreviation: NPADiBzQn); and the like can be given. In particular,among bipolar substances, a substance having a hole mobility and anelectron mobility of 1×10⁻⁶ cm²/Vs or more is preferable.

The light-emitting layer includes at least one kind of luminescentsubstance. A luminescent substance herein is a substance with excellentemission efficiency which can emit light of a desired wavelength. Thelight emitting layer in this embodiment mode is a layer (in other words,a layer including a host substance and a guest substance) in which astilbene derivative of the present invention is mixed and dispersed in alayer made of a substance (host substance) having a larger band gap (theenergy gap between a LUMO level and a HOMO level) than a band gap of thestilbene derivative of the present invention which serves as a guestsubstance (dopant). Alternatively, the light-emitting layer can have astructure in which a host substance is not used, that is, only astilbene derivative of the present invention is used for thelight-emitting layer. As for the light-emitting layer having eitherstructure, by using a stilbene derivative of the present invention for alight-emitting layer (or a part of a light-emitting layer), a bluelight-emitting element with excellent color purity can be obtained.

As a host substance which is combined with a stilbene derivative of thepresent invention to form a light-emitting layer,9-[4-(N-carbazolyl)phenyl]-10-phenyl anthracene (abbreviation: CzPA),4,4′-di(N-carbazolyl)biphenyl (abbreviation: CBP),bis[2-(2-hydroxyphenyl)benzoxazolato]zinc (abbreviation: Zn(BOX)₂),9,10-di(2-naphthyl)anthracene (abbreviation: DNA),4,4′,4″-tri(N-carbazolyl)triphenylamine (abbreviation: TCTA),2,2′,2″-(1,3,5-benzenetriyl)-tris(1-phenyl-1H-benzimidazole)(abbreviation: TPBi) or the like can be used.

The electron transporting layer is a layer which is excellent in anelectron transporting property, and specifically, the electrontransporting layer is preferably formed of an electron transportingsubstance or a bipolar substance, which has an electron mobility of1×10⁻⁶ cm²/Vs or more. The electron transporting substance is asubstance having higher electron mobility than hole mobility, and ispreferably a substance having a value of a ratio of electron mobility tohole mobility (=electron mobility/hole mobility) of more than 100.

As specific examples of an electron transporting substance, a metalcomplex having a quinoline skeleton or a benzoquinoline skeleton such astris(8-quinolinolato)aluminum (hereinafter, referred to as “Alq₃”),tris(4-methyl-8-quinolinolato)aluminum (hereinafter, referred to asAlmq₃), or bis(10-hydroxybenzo[h]quinolinato)beryllium (hereinafter,referred to as “BeBq₂”);bis(2-methyl-8-quinolinolato)(4-phenylphenolato)aluminum (hereinafter,referred to as “BAlq”) which is a mixed ligand complex; or the like ispreferable.

Alternatively, a metal complex having an oxazole-based or thiazole-basedligand such as bis[2-(2-hydroxyphenyl)benzoxazolato]zinc (hereinafter,referred to as “Zn(BOX)₂”) orbis[2-(2-hydroxyphenyl)benzothiazolato]zinc (hereinafter, referred to as“Zn(BTZ)₂”) can also be used.

Furthermore, an oxadiazole derivative such as2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole (hereinafter,referred to as “PBD”) or1,3-bis[5-(p-tert-butylphenyl)-1,3,4-oxadiazol-2-yl]benzene(hereinafter, referred to as “OXD-7”) can be used as well as the metalcomplexes described above.

Further alternatively, a triazole derivative such as3-(4-tert-butylphenyl)-4-phenyl-5-(4-biphenylyl)-1,2,4-triazole(hereinafter, referred to as “TAZ”) or3-(4-tert-butylphenyl)-4-(4-ethylphenyl)-5-(4-biphenylyl)-1,2,4-triazole(hereinafter, referred to as “p-EtTAZ”); a phenanthroline derivativesuch as bathophenanthroline (hereinafter, referred to as “BPhen”) orbathocuproin (hereinafter, referred to as “BCP”); and, further,4,4-bis(5-methylbenzoxazolyl-2-yl)stilbene (hereinafter, referred to as“BzOs”); or the like can be used as well as the metal complexesdescribed above.

As specific examples of the bipolar substance, the above-mentionedsubstances can also be used.

As a hole blocking substance, BAlq, OXD-7, TAZ, p-EtTAZ, BPhen, BCP, orthe like which are mentioned above can be used.

As described above, by manufacturing a light-emitting element in which astilbene derivative of the present invention is used for alight-emitting layer or a part of a light-emitting layer, a bluelight-emitting element with excellent color purity can be obtained.

Embodiment Mode 6

In this embodiment mode, as an example of a thin film transistor (TFT)which can provide a light-emitting device by combining with alight-emitting element including a stilbene derivative of the presentinvention, a single gate TFT having a top gate structure is describedwith reference to FIG. 2.

As shown in FIG. 2, a TFT 208 is formed over a substrate 201. A drainelectrode 207 b of the TFT 208 is electrically connected to a firstelectrode 209 of a light-emitting element. Although not shown, a secondelectrode is formed over the first electrode 209 with a layer includinga luminescent substance therebetween and thus, the light-emittingelement as described in Embodiment Mode 5 is formed. With such astructure, the TFT 208 can control driving of the light-emittingelement.

There is no particular limitation on the kind of the substrate 201, anda glass substrate, a quartz substrate, a silicon substrate, a metalsubstrate (for example, a stainless steel substrate), a ceramicsubstrate, a plastic substrate (for example, an acrylic substrate), orthe like can be used.

In addition, although not shown, an insulating film (a base film) formedusing silicon oxide, silicon nitride, silicon nitride containing oxygen,silicon oxide containing nitrogen, or the like may be formed between thesubstrate 201 and the TFT 208 by a method such as a plasma CVD method ora sputtering method. Note that the insulating film may be formed as asingle layer film or a multilayer film. By providing an insulating filmbetween the substrate 201 and the TFT 208, impurities can be preventedfrom diffusing into the TFT 208 from the substrate 201.

A source region 202 a, a drain region 202 b, and a channel formingregion 203 in FIG. 2 are formed of a semiconductor film. As a materialfor the semiconductor film, a material containing silicon,silicon-germanium (SiGe), or the like as a main component can be used.As the semiconductor film, an amorphous semiconductor film or acrystalline semiconductor film can be used. In this embodiment mode, acase where the crystalline semiconductor film is used as thesemiconductor film is described. The semiconductor film can be formed bya method such as a plasma CVD method or a sputtering method. Thethickness of the semiconductor film is 10 to 150 nm, preferably 30 to 70nm.

The crystalline semiconductor film can be formed by crystallizing anamorphous semiconductor film by heating or laser irradiation.Alternatively, a crystalline semiconductor film can be formed in a stageof film formation. For example, the heat-assisted or plasma-assistedcrystallization using a fluorine-based gas such as GeF₄ or F₂, and asilane-based gas such as SiH₄ or Si₂H₆ can be adopted to form acrystalline semiconductor film.

The source region 202 a and the drain region 202 b are regions in whichan impurity element is added to the crystalline semiconductor film. Theimpurity element is an element which can impart one conductivity type tothe semiconductor film, and typically, phosphorus (P) or the like can begiven as an impurity element imparting an n-type conductivity type, andboron (B) or the like can be given as an impurity element imparting ap-type conductivity type. When the first electrode 209 serves as ananode, an impurity element imparting p-type conductivity is preferablyadded. On the other hand, when the first electrode 209 serves as acathode, an impurity element imparting n-type conductivity is preferablyadded. In the TFT structure shown in this embodiment mode, after forminga crystalline semiconductor film, an impurity is added to thecrystalline semiconductor film by using a gate electrode 205 as a mask.

A gate insulating film 204 formed to cover the source region 202 a, thedrain region 202 b, and the channel forming region 203 is formed usingan insulator such as silicon oxide, silicon nitride, silicon nitridecontaining oxygen, or silicon oxide containing nitrogen by afilm-formation method such as a plasma CVD method or a sputteringmethod. The gate insulating film 204 may be formed to have a singlelayer structure or a stacked structure. The thickness of the gateinsulating film 204 is preferably 10 to 150 nm, more preferably 30 to 70nm.

The gate electrode 205 can be formed using a conductive film made of ametal nitride such as tantalum nitride or titanium nitride, as well as ametal such as tungsten, aluminum, molybdenum, tantalum, titanium,copper, chromium, or niobium. The conductive film can be formed by amethod such as a sputtering method. The gate electrode 205 may be formedto have a single layer structure or a stacked structure. The thicknessof the gate electrode 205 is preferably greater than or equal to 200 nm,more preferably 300 to 700 nm.

An interlayer insulating film 206 formed to cover the source region 202a, the drain region 202 b, the channel forming region 203, and the gateelectrode 205 can be formed using an inorganic-based insulator such assilicon oxide, silicon nitride, silicon nitride including oxygen, orsilicon oxide including nitrogen. Besides, an organic resin such asacrylic resin, polyimide, or siloxane-based resin can be used. Note that“siloxane-based resin” is a compound including an element such assilicon (Si), oxygen (O) or hydrogen (H) and further including anSi—O—Si bond (siloxane bond). Such an insulator described above can beformed by a method such as a plasma CVD method, a sputtering method, acoating method, or a spin coating method. The thickness of theinterlayer insulating film 206 is preferably 0.3 to 2 μm, morepreferably 0.5 to 1 μm.

A source electrode 207 a and a drain electrode 207 b formed over theinterlayer insulating film 206 are electrically connected to the sourceregion 202 a and the drain region 202 b, respectively. The sourceelectrode 207 a and the drain electrode 207 b can be formed of anelement selected from tantalum, tungsten, titanium, molybdenum,aluminum, copper, chromium, niobium, and the like; or an alloy materialor a compound material containing any of the above-described elements asits main component. Alternatively, a semiconductor material typified bypolycrystalline silicon doped with an impurity element such asphosphorus can be used.

The source electrode 207 and the drain electrode 207 b may be formed tohave a single layer structure or a stacked structure. As a specificexample of a case where a two-layer structure is employed as the stackedstructure, for example, a structure can be given, in which a tantalumnitride film and a tungsten film, a tungsten nitride film and a tungstenfilm, or a molybdenum nitride film and a molybdenum film are stacked.The thicknesses of the source electrode 207 a and the drain electrode207 b are preferably greater than or equal to 200 nm, more preferably300 to 700 nm.

The drain electrode 207 b is electrically connected to the firstelectrode 209 of the light-emitting element. The material for formingthe first electrode 209 is described in Embodiment Mode 5 and thedescription is omitted here.

An insulator 210 is formed to cover the source electrode 207 a, thedrain electrode 207 b, and the peripheral portion of the first electrode209. The insulator 210 is preferably formed to have a curvature on itsside. The insulator 210 can be formed using acrylic resin, polyimide,silicon oxide, silicon nitride, siloxane-based resin, or the like.

This embodiment mode describes the case where the TFT 208 is a singlegate TFT having a top gate structure; however, the present invention isnot limited to this structure. That is, a TFT having a bottom gatestructure or a multigate type having plural gate electrodes may be used.Further, a TFT having an LDD (Light Doped Drain) structure which has alow concentration impurity region including an impurity at lowerconcentration than a drain region, between a channel forming region anda drain region, may be employed. Furthermore, a transistor with agate-overlapped LDD structure in which a low concentration impurityregion formed between a channel forming region and a drain regionoverlaps with a gate electrode, may be used.

By using a stilbene derivative of the present invention for alight-emitting layer of the light-emitting element in a light-emittingdevice having a TFT described in this embodiment mode and alight-emitting element connected to the TFT, a light-emitting deviceshowing blue emission with excellent color purity can be provided.

Embodiment Mode 7

In this embodiment mode, as an example of a thin film transistor (TFT)which can provide a light-emitting device by combining with alight-emitting element including a stilbene derivative of the presentinvention, a channel-etch type TFT having a bottom gate structure isdescribed with reference to FIG. 3A and a channel-stop type TFT having abottom gate structure is described with reference to FIG. 3B.

As shown in FIG. 3A, a channel etch type TFT 308 having a bottom gatestructure is formed over a substrate 301. A drain electrode 306 b of theTFT 308 is electrically connected to a first electrode 309 of alight-emitting element.

Although not shown, a second electrode is formed over the firstelectrode 309 with a layer including a luminescent substancetherebetween. Thus, the light-emitting element as described inEmbodiment Mode 5 is formed. With such a structure, the TFT 308 cancontrol driving of the light-emitting element.

There is no particular limitation on the kind of the substrate 301, andthe same materials as the substrate 201 shown in Embodiment Mode 6 canbe used. In addition, an insulating film which can be provided betweenthe substrate 301 and the TFT 308 can be formed by the same method andusing the same material as in Embodiment Mode 6.

A gate electrode 302 is formed over the substrate 301. A gate insulatingfilm 303 is formed over the gate electrode 302. Note that the gateelectrode 302 and the gate insulating film 303 can be formed by the samemethod and using the same material as the gate electrode 205 and thegate insulating film 204, respectively, described in Embodiment Mode 6.

In a position of overlapping with the gate electrode 302 with the gateinsulating film 303 interposed therebetween, a channel forming region304 formed of a first semiconductor film is formed. The firstsemiconductor film can be formed by the same method and using the samematerial as the semiconductor film described in Embodiment Mode 6. Inthis embodiment mode, a case is described where an amorphoussemiconductor film is used as the first semiconductor film. Thethickness of the first semiconductor film used here is 10 to 150 nm,preferably 30 to 70 nm.

A source region 305 a and a drain region 305 b formed of a secondsemiconductor film are formed over the first semiconductor film. As thesecond semiconductor film, an amorphous semiconductor film or acrystalline semiconductor film, each of which contains silicon,silicon-germanium (SiGe), or the like as its main component and containsan impurity imparting an n-type or p-type conductivity type, can beused. In this embodiment mode, a case is described where an amorphoussemiconductor film is used as the second semiconductor film. The secondsemiconductor film is an amorphous semiconductor film including animpurity imparting an n-type or p-type conductivity type beforehand. Thesecond semiconductor film can be formed by a method such as a plasma CVDmethod. The thickness of the second semiconductor film used here is setfrom 10 to 150 nm, preferably 30 to 70 nm.

A source electrode 306 a and a drain electrode 306 b are formed over andin contact with the source region 305 a and the drain region 305 b,respectively. Note that the source electrode 306 a and the drainelectrode 306 b can be formed by the same method, using the samematerial, and with the same thickness as the source electrode 207 a andthe drain electrode 207 b shown in Embodiment Mode 6.

The TFT 308 includes the gate electrode 302, the gate insulating film303, the channel forming region 304, the source region 305 a, the drainregion 305 b, the source electrode 306 a, and the drain electrode 306 b.An interlayer insulating film 307 is formed to cover the TFT 308. Theinterlayer insulating film 307 can be formed using the same material asthe interlayer insulating film 206 described in Embodiment Mode 6.

The drain electrode 306 b is electrically connected to the firstelectrode 309 of the light-emitting element through an opening portionformed in part of the interlayer insulating film 307. The method,material, and thickness for forming the first electrode 309 aredescribed in Embodiment Mode 5 and the description is omitted here.

An insulator 310 formed to cover the TFT 308 and the peripheral portionof the first electrode 309 can be formed by the same method, using thesame material, and with the same thickness as the insulator 210 shown inEmbodiment Mode 6.

Next, a channel-stop type TFT 328 having a bottom gate structure isdescribed with reference to FIG. 3B. The TFT 328 is formed over asubstrate 321, and a drain electrode 326 b of the TFT 328 iselectrically connected to a first electrode 329 of the light-emittingelement. Although not shown, a second electrode is formed over the firstelectrode 329 with a layer including a luminescent substancetherebetween. Thus, the light-emitting element as described inEmbodiment Mode 5 is formed. With such a structure, the TFT 328 cancontrol driving of the light-emitting element.

In the channel-stop type TFT 328 having a bottom gate structure shown inFIG. 3B, a protective film 331 is provided over a channel forming region324, in a position of overlapping with the gate electrode.

Note that the protective film 331 is a film having a function ofprotecting the first semiconductor film forming the channel formingregion 324 in order not to be etched when a second semiconductor filmand a conductive film are processed to form a source region 325 a, adrain region 325 b, a source electrode 326 a, and a drain electrode 326b. The protective film 331 may be formed using an insulating film suchas silicon oxide, silicon nitride, silicon nitride containing oxygen, orsilicon oxide containing oxygen by a film-formation method such as aplasma CVD method or a sputtering method.

In addition, a gate electrode 322, a gate insulating film 323, thechannel forming region 324, the source region 325 a, the drain region325 b, the source electrode 326 a, the drain electrode 326 b, aninterlayer insulating film 327, the first electrode 329, and aninsulator 330 shown in FIG. 3B may be formed by the same method, usingthe same material, and with the same thickness as the gate electrode302, the gate insulating film 303, the channel forming region 304, thesource region 305 a, the drain region 305 b, the source electrode 306 a,the drain electrode 306 b, the interlayer insulating film 307, the firstelectrode 309, and the insulator 310, respectively, described withreference to FIG. 3A. Thus, description made in FIG. 3A is referred to,and description of the method, material, and thickness thereof isomitted here.

By using a stilbene derivative of the present invention for alight-emitting layer of a light-emitting element in a light-emittingdevice having a TFT described in this embodiment mode and alight-emitting element connected to the TFT, a light-emitting deviceshowing blue emission with excellent color purity can be provided in thepresent invention.

Embodiment Mode 8

In this embodiment mode, a light-emitting device having a light-emittingelement manufactured using the present invention in a pixel portion isdescribed with reference to FIGS. 4A and 4B. Note that the structure ofa light-emitting device in this specification includes a control meanssuch as a driver circuit for driving the light-emitting element, as wellas the light-emitting element of the present invention.

FIG. 4A is a top view showing the light-emitting device, and FIG. 4B isa cross-sectional view taken along a line A-A′ of FIG. 4A. A referencenumeral 401 indicated by a dashed line denotes a driver circuit portion(a source side driver circuit); 402, a pixel portion; and 403, a drivercircuit portion (a gate side driver circuit). Reference numeral 404denotes a sealing substrate; reference numeral 405 denotes a sealant;and an inner side region surrounded by the sealant 405 is a space 407.

Reference numeral 408 denotes a wiring for transmitting signals input tothe source side driver circuit 401 and the gate side driver circuit 403and receives a video signal, a clock signal, a start signal, a resetsignal, and the like from an FPC (Flexible Printed Circuit) 409 servingas an external input terminal. Only the FPC is shown here, however, aprinted wiring board (PWB) may be attached to the FPC. In thisspecification, the light-emitting device includes the light-emittingdevice on which the FPC or the PWB is mounted as well as thelight-emitting device itself.

Next, a cross-sectional structure of the light-emitting device isdescribed with reference to FIG. 4B. In FIG. 4B, the source side drivercircuit 401 which is the driver circuit portion and the pixel portion402 are formed over an element substrate 410.

In this embodiment mode, as the source side driver circuit 401, a CMOScircuit which is obtained by combining an n-channel TFT 423 and ap-channel TFT 424 is formed. However, the TFT forming the driver circuitmay be a PMOS circuit or an NMOS circuit. Although a driver-integratedtype light-emitting device, in which the pixel portion and the drivercircuit are formed in an integrated manner over the substrate, is shownin this embodiment mode, the light-emitting device is not necessarilylimited to this structure. That is, a light-emitting device, in which adriver circuit portion fabricated over a substrate is attached to asubstrate over which a pixel portion is formed, can also bemanufactured.

The pixel portion 402 is formed of a plurality of pixels having aswitching TFT 411, a current control TFT 412, and a first electrode 413electrically connected to a drain of the current control TFT 412. Aninsulator 414 is formed to cover an end portion of the first electrode413. In this embodiment mode, the insulator 414 is formed using apositive type photosensitive acrylic resin film. Over the firstelectrode 413, a layer 416 including a luminescent substance and asecond electrode 417 are formed.

Here, it is desirable to use a material having a high work function as amaterial for forming the first electrode 413 in a case of serving thefirst electrode 413 as an anode. For example, a single layer structureusing an indium tin oxide (ITO) film, an indium zinc oxide (IZO) film, atitanium nitride film, a chromium film, a tungsten film, a Zn film, a Ptfilm, or the like; a two-layer structure of a film mainly containingtitanium nitride and a film mainly containing aluminum; a three-layerstructure of a titanium nitride film, a film mainly containing aluminum,and a titanium nitride film; or the like can be used. It is preferred toform the first electrode 413 as a stacked structure because a good ohmiccontact can be readily achieved between the first electrode 413 with thedrain electrode of the current control TFT 412.

The layer 416 including a luminescent substance can be formed by anevaporation method using an evaporation mask or an inkjet method. As thematerial which forms the layer 416 including a luminescent substance orthe structure of the layer 416 including a luminescent substance, thematerial and the structure described in Embodiment Mode 5 can beappropriately used; therefore, the description is omitted here.

Further, in this embodiment mode, a buffer layer is provided to be incontact with one electrode (an anode or a cathode) of the two electrodesof the light-emitting element, to be in contact with the two electrodes,or to be in contact with neither of the two electrodes.

The second electrode (cathode) 417 is formed over the layer 416including a luminescent substance.

By attaching the sealing substrate 404 to the element substrate 410 withthe sealant 405, a structure is obtained in which a light-emittingelement 418 is provided in the space 407 surrounded by the elementsubstrate 410, the sealing substrate 404, and the sealant 405. Astructure in which the space 407 is filled with an inert gas (nitrogenor argon) and a structure in which the space 407 is filled with thesealant 405 are preferable in order to suppress deterioration of alight-emitting element of the present invention.

As the sealant 405, it is preferable to use a material (for example, anepoxy-based resin) which does not transmit moisture and oxygen as littleas possible. Further, there is no particular limitation on a material tobe used for the sealing substrate 404, and a glass substrate, a quartzsubstrate, a silicon substrate, a metal substrate (for example, astainless steel substrate), a ceramic substrate, a plastic substrate(for example, an acrylic substrate), or the like can be used.

As described above, by manufacturing a light-emitting device with theuse of a stilbene derivative of the present invention, a light-emittingdevice showing blue emission with excellent color purity can beprovided. The light-emitting device shown in this embodiment mode can befreely combined with any of the structures shown in Embodiment Modes 1to 7.

Embodiment Mode 9

In this embodiment mode, an example is explained, in which alight-emitting element having a stilbene derivative manufacturedaccording to the present invention is applied to an electronic device.As specific examples of an electronic device, there are a video camera,a digital camera, a projector, a head mounted display (a goggle typedisplay), a car navigation system, a car stereo, a personal computer, agame machine, a mobile information terminal (e.g., a mobile computer, amobile phone, or an electronic book), an image reproducing deviceprovided with a recording medium (specifically, a device whichreproduces a recording medium such as Digital Versatile Disc (DVD) andis provided with a display which can display the image), and the like.Specific examples of an electronic device are shown in FIGS. 5A to 5C.

FIG. 5A shows a display device, which includes a chassis 1901, asupporting base 1902, a display portion 1903, a speaker portion 1904, avideo input terminal 1905, and the like. Since the light-emittingelement having a stilbene derivative described in the above embodimentmodes has excellent color purity of blue, by using the light-emittingelement for the display portion 1903, a display device which isexcellent in color reproducibility can be manufactured. The displaydevice includes all display devices used for displaying information, forexample, for a computer, for TV broadcast reception, or foradvertisement display.

FIG. 5B shows a computer, which includes a chassis 1911, a displayportion 1912, a keyboard 1913, an external connecting port 1914, apointing device 1915, and the like. Since the light-emitting elementhaving a stilbene derivative described in the above embodiment modes hasexcellent color purity of blue, by using the light-emitting element forthe display portion 1912, a computer which is excellent in colorreproducibility can be manufactured.

FIG. 5C shows a mobile phone, which is a typical example of a mobileinformation terminal. This mobile phone includes a chassis 1921, adisplay portion 1922, a sensor portion 1924, operation keys 1923, andthe like. The sensor portion 1924 includes an optical sensor element,and current consumption of the mobile phone can be reduced bycontrolling luminance of the display portion 1922 in accordance withilluminance obtained at the sensor portion 1924 or by controllingluminance of the operation key 1923 in accordance with the illuminanceobtained at the sensor portion 1924.

In addition, in the case of a mobile phone having an imaging functionsuch as a CCD, whether or not a person taking a picture looks into anoptical finder is detected based on the change in the amount of lightreceived by a sensor of the sensor portion 1924 provided in the vicinityof the optical finder. In the case where a person taking a picture looksinto the optical finder, power consumption can be suppressed by turningoff the display portion 1922. Since the light-emitting element having astilbene derivative described in the above embodiment modes hasexcellent color purity of blue, by using the light-emitting element forthe display portion 1922, a mobile phone which is excellent in colorreproducibility can be manufactured.

As described above, the applicable range of the light-emitting elementhaving a stilbene derivative manufactured according to the presentinvention is so wide that the light-emitting element having a stilbenederivative manufactured according to the present invention can be usedfor electronic devices in various fields. This embodiment mode can befreely combined with any of the above embodiment modes.

Embodiment 1

In this embodiment, an example of a synthetic method of a stilbenederivative of the present invention is explained. It is to be noted thata stilbene derivative of the present invention is not limited to beingmanufactured by the synthetic method described in this embodiment.

In this embodiment, an example of a synthetic method of(E)-4-{N-[4-(9H-carbazol-9-yl)phenyl]-N-phenyl}amino-4′-(9H-carbazol-9-yl)stilbene(hereinafter, abbreviated as “YGACzS”) which is an example of thestilbene derivative is described. A synthetic scheme of the substance isshown in the following Steps 1 to 4.

Step 1; Synthesis of 4-bromobenzyl triphenylphosphonium bromide

First, 25.2 g (101 mmol) of 4-bromobenzyl bromide and 100 mL of acetonewere placed in a 200 mL conical flask, and 29.1 g (111 mmol) oftriphenylphosphine was added thereto. This reaction mixture was stirredat room temperature for 23 hours. After the completion of the reaction,the precipitate in the reaction mixture was collected by suctionfiltration. 50.5 g of a white powdered solid, 4-bromobenzyltriphenylphosphonium bromide, which was the target substance, wasobtained in a yield of 97.6%. A synthetic scheme (a-1) of 4-bromobenzyltriphenylphosphonium bromide is shown below.

Step 2; Synthesis of (E)-4-bromo-4′-(9H-carbazol-9-yl)stilbene

Next, 9.44 g (18.4 mmol) of 4-bromobenzyl triphenylphosphonium bromideobtained in Step 1 and 5.00 g (18.4 mmol) of4-(9H-carbazol-9-yl)benzaldehyde were placed into a 300 mL three-neckflask, and nitrogen substitution was carried out in the three-neckflask. Then, 50 mL of tetrahydrofuran (THF) was added thereto. Asuspension in which 2.07 g (18.4 mmol) of potassium tert-butoxide wasmixed in 50 mL of THF was dropped into this mixture. After thecompletion of the dropping, the reaction mixture was stirred at roomtemperature for 24 hours.

After the completion of the reaction, water was added to the reactionmixture, and the precipitate was collected by suction filtration. 4.41 gof a yellow powdered solid, (E)-4-bromo-4′-(9H-carbazol-9-yl)stilbene,which was the target substance, was obtained in a yield of 56.4%. It wasconfirmed that (Z)-4-bromo-4′-(9H-carbazol-9-yl)stilbene which is anisomer of the target substance was included in the obtained filtrate. Asynthetic scheme (a-2) of (E)-4-bromo-4′-(9H-carbazol-9-yl)stilbene isshown below.

Step 3; Synthesis of N-[(4-(9H-carbazol-9-yl)]phenyl-N-phenylamine(hereinafter, abbreviated as “YGA”)

56.3 g (0.24 mol) of 1,4-dibromobenzene, 31.3 g (0.18 mol) of carbazole,4.6 g (0.024 mol) of copper iodide, 66.3 g (0.48 mol) of potassiumcarbonate, and 2.1 g (0.008 mol) of 18-crown-6-ether were placed into a300 mL three-neck flask, and nitrogen substitution was carried out inthe three-neck flask. 8 mL of1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (abbreviation: DMPU)was added to this mixture, and then the mixture was stirred at 180° C.for 6 hours under a nitrogen stream.

After the reaction mixture was cooled to room temperature, theprecipitate was removed by suction filtration, and the filtrate wasobtained. This filtrate was washed with a diluted hydrochloric acid, asaturated sodium hydrogencarbonate aqueous solution, and brine in thatorder, and then dried with magnesium sulfate. After the drying, thereaction mixture was filtered and the obtained filtrate wasconcentrated. The oily substance obtained by this concentration waspurified by silica gel column chromatography (hexane:ethyl acetate=9:1),and this was recrystallized with chloroform and hexane. 20.7 g of alight-brown plate-like crystal, which was the target substance, wasobtained in a yield of 35%. This compound was identified by a nuclearmagnetic resonance method (NMR) as N-(4-bromophenyl)carbazole.

¹H NMR of this compound is shown below.

¹H NMR (300 MHz, CDCl₃) δ=8.14 (d, J=7.8 Hz, 2H), 7.73 (d, J=8.7 Hz,2H), 7.46 (d, J=8.4 Hz, 2H), 7.42-7.26 (m, 6H).

Next, 5.4 g (17.0 mmol) of the obtained N-(4-bromophenyl)carbazole, 1.8mL (20.0 mmol) of aniline, 100 mg (0.17 mmol) ofbis(dibenzylideneacetone)palladium(0) (abbreviation: Pd(dba)₂), and 3.9g (40 mmol) of sodium tert-butoxide (abbreviation: tert-BuONa) were putinto a 200 mL three-neck flask, and nitrogen substitution was carriedout in the three-neck flask. After a 10 wt % hexane solution of 0.1 mLof tri-tert-butylphosphine (abbreviation: P(tert-Bu)₃) and 50 mL ofdehydrated toluene were added to this mixture, stirring was performed at80° C. for 6 hours under a nitrogen stream.

Then, the reaction mixture was filtered through Florisil, celite, andalumina. The filtrate obtained by the filtration was washed with waterand brine, and then dried with magnesium sulfate. The reaction mixturewas filtered, and the filtrate was concentrated, and an oily substancewas obtained. This substance was purified by silica gel columnchromatography (hexane:ethyl acetate=9:1), and 4.1 g of the targetsubstance was obtained in a yield of 73%. This compound was identifiedby a nuclear magnetic resonance method (NMR) asN-[(4-(9H-carbazol-9-yl)]phenyl-N-phenylamine (abbreviation: YGA).

¹H NMR data of this compound is shown below.

¹H NMR (300 MHz, DMSO-d₆) δ=8.47 (s, 1H) 8.22 (d, J=7.8 Hz, 2H),7.44-7.16 (m, 14H), 6.92-6.87 (m, 1H)

A synthetic scheme (a-3) of YGA is shown below.

Step 4; Synthesis of(E)-4-{N-[4-(9H-carbazol-9-yl)phenyl]-N-phenyl}amino-4′-(9H-carbazol-9-yl)stilbene(YGACzS)

Next, 1.0 g (2.4 mmol) of the (E)-4-bromo-4′-(carbazol-9-yl)stilbeneobtained in Step 2, 0.87 g (2.6 mmol) of theN-(4-carbazol-9-yl)-N-phenylamine (YGA) obtained in Step 3, 0.068 g(0.12 mmol) of bis(dibenzylideneacetone)palladium(0), and 1.1 g (12mmol) of sodium tert-butoxide were placed in a 100 mL three-neck flask,and nitrogen substitution was carried out in the three-neck flask. 20 mLof toluene and 0.095 g (0.047 mmol) of tri-tert-butylphosphine (10%hexane solution) were added to this mixture. This reaction mixture wasstirred at 80° C. for 7 hours.

After the completion of the reaction, the reaction solution was washedwith water, and the aqueous phase was extracted with ethyl acetate. Theextracted solution combined with the organic phase was dried withmagnesium sulfate. After the drying, the mixture was subjected tosuction filtration and the filtrate was concentrated. The obtained solidwas dissolved in a mixed solvent of toluene and chloroform, and theresulting solution was subjected to suction filtration through Florisil,celite, and alumina. The filtrate was concentrated, and the obtainedsolid was recrystallized with a mixed solvent of chloroform and hexane.1.5 g of a light-yellow powdered solid, which was the target substance,was obtained in a yield of 92%. This compound was identified by anuclear magnetic resonance method (NMR) as(E)-4-{N-[4-(9H-carbazol-9-yl)phenyl]-N-phenyl}amino-4′-(9H-carbazol-9-yl)stilbene(YGACzS).

A synthetic scheme (a-4) of YGACzS is shown below.

¹H NMR data of the obtained YGACzS is shown below. FIGS. 6A and 6B areeach a ¹H NMR chart, and FIG. 6B is an enlarged chart of the 7 ppm to8.5 ppm range in FIG. 6A.

¹H NMR (CDCl₃, 300 MHz): δ=7.10-7.57 (m, 29H), 7.73 (d, J=8.1 Hz, 2H),8.15 (d, J=7.8 Hz, 4H)

Thermogravimetry-differential thermal analysis (TG-DTA) was performed onthe obtained YGACzS. The measurement performed using athermogravimetric/differential thermal analyzer (TG/DTA 320,manufactured by Seiko Instruments Inc.) revealed that the 5% weight losstemperature was 437.8° C., which means that the YGACzS is a materialhaving favorable heat resistance.

FIG. 7A shows an absorption spectrum of YGACzS in toluene. In FIG. 7A,the horizontal axis indicates the wavelength (nm) and the vertical axisindicates the absorption intensity (arbitrary unit).

FIG. 7B shows an absorption spectrum in a thin film state obtained bydepositing the obtained YGACzS by an evaporation method. In FIG. 7B, thehorizontal axis indicates the wavelength (nm) and the vertical axisindicates the absorption intensity (arbitrary unit). The absorptionspectra were measured using an ultraviolet-visible spectrophotometer(V-550, manufactured by JASCO Corporation).

FIG. 8A shows an emission spectrum (excitation wavelength: 370 nm) ofthe obtained YGACzS in toluene. In FIG. 8A, the horizontal axisindicates the wavelength (nm) and the vertical axis indicates theemission intensity (arbitrary unit). It is apparent from FIG. 8A thatlight emission from the YGACzS has a peak at 432 nm in the toluenesolution. Further, emission color of the YGACzS in the toluene solutionwas visually identified as being bluish.

FIG. 8B shows an emission spectrum (excitation wavelength: 387 nm) in athin film state obtained by depositing the obtained YGACzS by anevaporation method. In FIG. 8B, the horizontal axis indicates thewavelength (nm) and the vertical axis indicates the emission intensity(arbitrary unit). It is apparent from FIG. 8B that light emission fromthe YGACzS has a peak at 458 nm in the thin film state. Further,emission color of the YGACzS in the thin film state was able to bevisually identified as being bluish. The emission spectrum was measuredusing a fluorescence spectrophotometer (FS920, manufactured by HamamatsuPhotonics Corporation).

The obtained YGACzS was deposited by an evaporation method, and anionization potential of YGACzS in a thin film state was estimated to be5.35 eV by using a photoelectron spectroscopy device (AC-2, manufacturedby Riken Keiki Co., Ltd.). From the measurement result of the ionizationpotential, it was found that the value of the HOMO level was −5.35 eV.Further, the absorption spectrum of the compound in a thin film statewas measured using an UV-visible spectrophotometer (V-550, manufacturedby JASCO Corporation). The absorption edge of the longer wavelength sidewas obtained from a Tauc plot assuming direct transition. The LUMO levelwas obtained by considering the energy of the absorption edge as a bandgap (2.91 eV). The LUMO level was −2.44 eV.

An oxidation reduction characteristic of the YGACzS was measured by acyclic voltammetry (CV) technique. An electrochemical analyzer (ALSmodel 600A, manufactured by BAS Inc.) was used for the measurement.

The solution for the CV measurement was prepared by using dehydrateddimethylformamide (DMF) (produced by Aldrich Corp., 99.8%, catalognumber: 22705-6) as a solvent, dissolving a supporting electrolyte,tetra-n-butylammonium perchlorate (n-Bu₄NClO₄) (produced by TokyoChemical Industry Co., Ltd., catalog number: T0836), at a concentrationof 100 mmol/L, and then dissolving YGACzS which was the object ofmeasurement at a concentration of 1 mmol/L.

A platinum electrode (a PTE platinum electrode, manufactured by BASInc.) was used as a working electrode, a platinum electrode (a Ptcounter electrode (5 cm) for VC-3 use, manufactured by BAS Inc.) wasused as an auxiliary electrode, and an Ag/Ag⁺ electrode (an RE5non-aqueous solvent reference electrode, manufactured by BAS Inc.) wasused as a reference electrode. The measurement was performed at roomtemperature. A scan in which the potential of the working electrode withrespect to the reference electrode was varied from 0.4 V to −0.03 Vafter changing it from −0.03 V to 0.4 V was regarded as one cycle, andthe scan was performed for 100 cycles with respect to both the oxidationregion and the reduction region. The scan rate of the CV measurement wasset at 0.1 V/s.

FIG. 9A shows results of a measurement of oxidation characteristics ofthe YGACzS. In FIG. 9A, the horizontal axis indicates a potential (V) ofthe working electrode with respect to the reference electrode, and thevertical axis indicates the amount of current (μA) flowing between theworking electrode and the auxiliary electrode. It can be seen from FIG.9A that the oxidation potential was 0.55 V (vs. Ag/Ag⁺ electrode).

FIG. 9B shows results of a measurement of a reduction characteristic ofYGACzS. In FIG. 9B, the horizontal axis indicates a potential (V) of theworking electrode with respect to the reference electrode, and thevertical axis indicates a value of current (μA) flowing between theworking electrode and the auxiliary electrode. It can be seen from FIG.9B that the reduction potential was −2.44 V (vs. Ag/Ag⁺ electrode).Although 100-cycle scans were conducted, the peak position and the peakintensity of the CV curve hardly changed. Therefore, it can be concludedthat YGACzS of the present invention is very stable with respect to therepeated process between the reduction and following oxidation.

Embodiment 2

In this embodiment, a synthetic method of a stilbene derivative which isdifferent from the stilbene derivative described in Embodiment 1 isdescribed.

In this embodiment, an example of a synthetic method of(E)-4-{N-[4-(9H-carbazol-9-yl)phenyl]-N-phenyl}amino-4′-diphenylaminostilbene(hereinafter, abbreviated as “YGADPhAS”) which is an example of astilbene derivative, is described. A synthetic scheme of the substanceis shown in the following Steps 1 to 4.

Step 1; Synthesis of 4-bromobenzyl triphenylphosphonium bromide

First, 25.2 g (101 mmol) of 4-bromobenzyl bromide and 100 mL of acetonewere placed in a 200 mL conical flask, and 29.1 g (111 mmol) oftriphenylphosphine was added thereto. This reaction mixture was stirredat room temperature for 23 hours. After the completion of the reaction,the precipitate in the reaction mixture was collected by suctionfiltration. 50.5 g of a white powdered solid, 4-bromobenzyltriphenylphosphonium bromide, which was the target substance, wasobtained in a yield of 97.6%. A synthetic scheme (b-1) of 4-bromobenzyltriphenylphosphonium bromide is shown below.

Step 2; Synthesis of (E)-4-bromo-4′-(N,N-diphenyl)aminostilbene

Next, 5.77 g (11.3 mmol) of 4-bromobenzyl triphenylphosphonium bromideobtained in Step 1 and 3.08 g (11.3 mmol) of 4-(N,N-diphenyl)aminobenzaldehyde were placed into a 300 mL three-neck flask, and nitrogensubstitution was carried out in the three-neck flask. Then, 50 mL oftetrahydrofuran (THF) was added to this mixture. Further, a suspensionin which 1.26 g (11.3 mmol) of potassium tert-butoxide was mixed in 30mL of THF was dropped to this mixture.

After the completion of the drop, the reaction mixture was stirred atroom temperature for 24 hours. After the completion of the reaction,water was added to the reaction mixture, and the precipitate wascollected by suction filtration. 1.50 g of a light yellow powderedsolid, (E)-4-bromo-4′-(N,N-diphenyl)aminostilbene], which was the targetsubstance, was obtained in a yield of 31.2%. It was confirmed that(Z)-4-bromo-4′-(N,N-diphenyl)aminostilbene] was contained in thefiltrate obtained by the suction filtration. A synthetic scheme (b-2) of(E)-4-bromo-4′-(N,N-diphenyl)aminostilbene is shown below.

Step 3; Synthesis of N-[4-(9H-carbazol-9-yl)]phenyl-N-phenylamine (YGA)

YGA is the same as the substance described in Step 3 of Embodiment 1;therefore, its synthesis will not be described here.

Step 4; Synthesis of(E)-4-{N-[4-(9H-carbazol-9-yl)phenyl]-N-phenyl}amino-4′-diphenylaminostilbene(YGADPhAS)

Next, 1.0 g (2.4 mmol) of (E)-4-bromo-4′-(N,N-diphenyl)aminostilbeneobtained in Step 2, 0.86 g (2.6 mmol) ofN-[4-(9H-carbazol-9-yl)]phenyl-N-phenylamine (YGA) obtained in Step 3,0.067 g (0.12 mmol) of bis(dibenzylideneacetone)palladium(0), and 1.1 g(12 mmol) of sodium tert-butoxide were placed in a 100 mL three-neckflask, and nitrogen substitution was carried out in the three-neckflask.

20 mL of toluene and 0.10 g (0.047 mmol) of tri-tert-butylphosphine (10%hexane solution) were added to this mixture. This reaction mixture wasstirred at 80° C. for 6 hours. After the completion of the reaction, thereaction solution was washed with water, and the aqueous phase wasextracted with ethyl acetate. The extracted solution combined with theorganic phase was dried with magnesium sulfate. After the drying, thismixture was subjected to suction filtration and the filtrate wasconcentrated. The obtained solid was dissolved in toluene, and theresulting solution was subjected to suction filtration through Florisil,celite, and alumina.

The filtrate was concentrated, and the obtained solid was recrystallizedwith a mixed solvent of chloroform and hexane. 0.26 g of a yellowpowdered solid, which was the target substance, was obtained in a yieldof 16%. This compound was identified by a nuclear magnetic resonancemethod (NMR) as(E)-4-{N-[4-(9H-carbazol-9-yl)phenyl]-N-phenyl}amino-4′-diphenylaminostilbene(abbreviation: YGADPhAS). A synthetic scheme (b-3) of YGADPhAS is shownbelow.

¹H NMR data of the obtained YGADPhAS is shown below. FIGS. 10A and 10Bare each a ¹H NMR chart, and FIG. 10B is an enlarged chart of the 6.5ppm to 8.5 ppm range in FIG. 10A.

¹H NMR (CDCl₃, 300 MHz): δ=6.98-7.45 (m, 35H), 8.14 (d, J=7.2 Hz, 2H)

Thermogravimetry-differential thermal analysis (TG-DTA) was performed onthe obtained YGADPhAS. The measurement performed using athermogravimetric/differential thermal analyzer (TG/DTA 320,manufactured by Seiko Instruments Inc.) revealed that the temperature of5% weight loss is 415.8° C., which means that the YGADPhAS is a materialhaving good heat resistance.

FIG. 11A shows an absorption spectrum of YGADPhAS in toluene. In FIG.11A, the horizontal axis indicates the wavelength (nm) and the verticalaxis indicates the absorption intensity (arbitrary unit).

FIG. 11B shows an absorption spectrum in a thin film state obtained bydepositing the obtained YGADPhAS by an evaporation method. In FIG. 11B,the horizontal axis indicates the wavelength (nm) and the vertical axisindicates the absorption intensity (arbitrary unit). The absorptionspectra were measured using an ultraviolet-visible spectrophotometer(V-550, manufactured by JASCO Corporation).

FIG. 12A shows an emission spectrum (excitation wavelength: 390 nm) of atoluene solution of the obtained YGADPhAS. In FIG. 12A, the horizontalaxis indicates the wavelength (nm) and the vertical axis indicates theemission intensity (arbitrary unit). It is apparent from FIG. 12A thatlight emission from the YGADPhAS has peaks at 408 nm and 431 nm in thetoluene solution. Further, emission color of the YGADPhAS in the toluenesolution was visually identified as being bluish.

FIG. 12B shows an emission spectrum (excitation wavelength: 397 nm) inthe thin film state obtained by depositing the obtained YGADPhAS by anevaporation method. In FIG. 12B, the horizontal axis indicates thewavelength (nm) and the vertical axis indicates the emission intensity(arbitrary unit). It is apparent from FIG. 12B that light emission fromthe YGADPhAS has a peak at 511 nm in the thin film state. Further,emission color of the YGADPhAS in the thin film state was visuallyidentified as being bluish. The emission spectra were measured using afluorescence spectrophotometer (FS920, manufactured by HamamatsuPhotonics Corporation).

The obtained YGADPhAS was deposited by an evaporation method, and anionization potential of the compound in a thin film state was measuredusing a photoelectron spectroscopy device (AC-2, manufactured by RikenKeiki Co., Ltd.). The measurement result was 5.22 eV, which means thatthe value of the HOMO level was −5.22 eV. Further, the absorptionspectrum of the compound in a thin film state was measured using aUV-visible spectrophotometer (V-550, manufactured by JASCO Corporation).The absorption edge on the longer wavelength side was obtained from aTauc plot assuming direct transition. The LUMO level was obtained byconsidering the energy of the absorption edge as a band gap (2.82 eV).The LUMO level was −2.40 eV.

Subsequently, oxidation characteristics of the YGADPhAS were measured bya cyclic voltammetry (CV) technique. An electrochemical analyzer (ALSmodel 600A, manufactured by BAS Inc.) was used for the measurement.

The solution for the CV measurement was prepared by using dehydrateddimethylformamide (DMF) (produced by Aldrich Corp., 99.8%, catalognumber: 22705-6) as a solvent, dissolving a supporting electrolyte oftetra-n-butylammonium perchlorate (n-Bu₄NClO₄) (produced by TokyoChemical Industry Co., Ltd., catalog number: T0836) at a concentrationof 100 mmol/L, and then dissolving the YGADPhAS which was the object ofmeasurement at a concentration of 1 mmol/L.

A platinum electrode (PTE platinum electrode, manufactured by BAS Inc.)was used as a working electrode, a platinum electrode (Pt counterelectrode (5 cm) for VC-3 use, manufactured by BAS Inc.) was used as anauxiliary electrode, and an Ag/Ag⁺ electrode (RE5 non-aqueous solventreference electrode, manufactured by BAS Inc.) was used as a referenceelectrode. The measurement was performed at room temperature. A scan inwhich the potential of the working electrode with respect to thereference electrode was varied from 0.4 V to −0.03 V after being changedfrom −0.03 V to 0.4 V was regarded as one cycle, and the scan wasperformed for 100 cycles. The scan rate of the CV measurement was 0.1V/s.

FIG. 13A and FIG. 13B show the results of the measurement of theoxidation characteristics and reduction characteristics of the YGADPhAS,respectively. In FIG. 13, the horizontal axis indicates a potential (V)of the working electrode with respect to the reference electrode, andthe vertical axis indicates the amount of current (μA) flowing betweenthe working electrode and the auxiliary electrode. From FIG. 13, it canbe seen that the oxidation potential was 0.34 V (vs. Ag/Ag⁺ electrode).Despite the fact that the scan was repeated for 100 cycles, the peakposition and the peak intensity of the CV curve hardly change before andafter the measurement. Thus, it was concluded that YGADPhAS of thepresent invention is very stable with respect to the repeated processbetween the oxidation and following reduction.

Embodiment 3

In this embodiment, a synthetic method ofN-{4-[(E)-4-(9H-carbazol-9-yl)styryl]phenyl}-N,9-diphenyl-9H-carbazol-3-aminerepresented by the following structure (hereinafter, abbreviated as“PCACzS”) in which A¹¹ corresponds to the general formula (1-2) of thegeneral formula (3) is shown.

First, (E)-4-bromo-4′-(9H-carbazol-9-yl)stilbene was synthesized inaccordance with the synthetic schemes (a-1) and (a-2) shown inEmbodiment 1. Then, in a 50 mL three-neck flask, 620 mg (1.5 mmol) of(E)-4-bromo-4′-(9H-carbazol-9-yl)stilbene; 500 mg (1.5 mmol) ofN,9-diphenyl-9H-carbazol-3-amine (abbreviation: PCA); 55 mg (0.1 mmol)of bis(dibenzylideneacetone)palladium(0); and a suspension of 200 mg(2.0 mmol) of sodium tert-butoxide, 15 mL of dehydrated xylene, and 600μL (0.3 mmol) of tri-tert-butylphosphine (10% hexane solution) wereheated and stirred at 110° C. for 11 hours under a nitrogen atmosphere.

After the completion of the reaction, approximately 200 mL of toluenewas added to this suspension, and the mixture was subjected to suctionfiltration through Florisil, alumina, and celite. The obtained filtratewas washed with water and dried with magnesium sulfate. This suspensionwas filtered through Florisil, alumina, and celite, and the obtainedfiltrate was concentrated. This concentrate was subjected to silica gelcolumn chromatography (a developing solvent was a mixed solvent oftoluene and hexane), and the target substance was obtained. The obtainedtarget substance was recrystallized with an acetate:hexane mixedsolvent.

140 mg ofN-{4-[(E)-4-(9H-carbazol-9-yl)styryl]phenyl}-N,9-diphenyl-9H-carbazol-3-amine(abbreviation: PCACzS), a yellow powder which was the target substance,was obtained in a yield of 14%. Rf values in silica gel thin layerchromatography (TLC) (in the developing solvent, hexane:ethylacetate=10:1) were as follows: the target substance was 0.43,(E)-4-bromo-4′-(9H-carbazol-9-yl)stilbene was 0.60, and PCA was 0.35.

¹H NMR data is shown below. FIGS. 26A and 26B are each a ¹H NMR chart,and FIG. 26B is an enlarged chart of the 6 ppm to 9 ppm range in FIG.26A.

¹H NMR (CDCl₃, 300 MHz): δ=6.99-7.72 (m, 31H), 7.96 (d, J=2.4 Hz, 1H),8.02 (d, J=7.8 Hz, 1H), 8.15 (d, J=7.3 Hz, 2H)

FIG. 27 shows an absorption spectrum of PCACzS in toluene. Thehorizontal axis indicates the wavelength (nm) and the vertical axisindicates the absorption intensity (arbitrary unit). The sample solutionwas put into a quartz cell, and measurement was carried out by using anultraviolet-visible spectrophotometer (V-550, manufactured by JASCOCorporation). A spectrum in which absorption spectra of the quartz andtoluene are abstracted from an absorption spectrum of the sample isshown in FIG. 27.

FIG. 28 shows an emission spectrum of PCACzS in toluene. In FIG. 28, thehorizontal axis indicates the wavelength (nm) and the vertical axisindicates the emission intensity (arbitrary unit). It was found thatlight emission had emission peaks at 460 nm and 473 nm in the toluenesolution (excitation light was 375 nm). Further, emission color in thetoluene solution was visually identified as being bluish. The emissionspectrum was measured using a fluorescence spectrophotometer (FS920,manufactured by Hamamatsu Photonics Corporation).

Thermogravimetry-differential thermal analysis (TG-DTA) was performed onPCACzS using a high vacuum differential type differential thermalbalance (type DTA2410SA, manufactured by Bruker AXS K. K.). Themeasurement performed under atmospheric air showed the temperature of 5%weight loss at 455° C., which means that the YGACzS has good heatresistance.

Embodiment 4

In this embodiment, a synthetic method ofN-{4-[(E)-4-(diphenylamino)styryl]phenyl}-N,N′,N′-triphenyl-1,4-phenylenediaminerepresented by the following structure (hereinafter, abbreviated as“DPAPhAS”) in which A¹¹ corresponds to the general formula (1-1) of thegeneral formula (1) is shown.

First, (E)-4-bromo-4′-(N,N-diphenyl)aminostilbene was synthesized inaccordance with synthetic schemes (b-1) and (b-2) shown in Embodiment 2.Then, in a 50 mL three-neck flask, 490 mg (1.2 mmol) of(E)-4-bromo-4′-(N,N-diphenyl)aminostilbene; 400 mg (1.2 mmol) ofN,N,N′-triphenyl-1,4-phenylenediamine (abbreviation: DPA); 55 mg (0.1mmol) of bis(dibenzylideneacetone)palladium(0); and a suspension of 200mg (2.0 mmol) of sodium tert-butoxide, 15 mL of dehydrated xylene, and600 μL (0.3 mmol) of tri-tert-butylphosphine (10% hexane solution) wereheated and stirred at 110° C. for 7 hours under a nitrogen atmosphere.

After the completion of the reaction, approximately 200 mL of toluenewas added to this suspension, and the mixture was subjected to suctionfiltration through Florisil, alumina, and celite. The obtained filtratewas washed with water and dried with magnesium sulfate. This suspensionwas filtered through Florisil, alumina, and celite, and the obtainedfiltrate was concentrated. This concentrate was subjected to silica gelcolumn chromatography (a developing solvent was a mixed solution oftoluene and hexane), and the target substance was obtained. The obtainedtarget substance was recrystallized with an acetate:hexane mixedsolvent.

480 mg ofN-{4-[(E)-4-(diphenylamino)styryl]phenyl}-N,N′,N′-triphenyl-1,4-phenylenediamine(abbreviation: DPAPhAS), a yellow powder which was the target substance,was obtained in a yield of 59%. Rf values in silica gel thin layerchromatography (TLC) (in the developing solvent, hexane:ethylacetate=10:1) were as follows: the target substance was 0.45,(E)-4-bromo-4′-(N,N-diphenyl)aminostilbene was 0.55, and DPA was 0.34.

¹H NMR data is shown below. FIGS. 29A and 29B are each a ¹H NMR chart,and FIG. 29B is an enlarged chart of the 6 ppm to 9 ppm range in FIG.29A.

¹H NMR (CDCl₃, 300 MHz): δ=6.93 (s, 2H), 6.98-7.27 (m, 33H), 7.35 (d,J=8.4 Hz, 4H)

FIG. 30 shows an absorption spectrum of DPAPhAS in toluene. Thehorizontal axis indicates the wavelength (nm) and the vertical axisindicates the absorption intensity (arbitrary unit). The sample solutionwas put into a quartz cell, and the measurement was conducted by usingan ultraviolet-visible spectrophotometer (V-550, manufactured by JASCOCorporation) A spectrum in which absorption spectra of the quartz andtoluene are abstracted from an absorption spectrum of the sample isshown in FIG. 30.

FIG. 31 shows an emission spectrum of DPAPhAS in toluene obtained byusing a fluorescence spectrophotometer (FS920, manufactured by HamamatsuPhotonics Corporation). The horizontal axis indicates the wavelength(nm) and the vertical axis indicates the emission intensity (arbitraryunit). It was found that light emission had emission peaks at 460 nm and472 nm in the toluene solution (excitation light was 375 nm). Further,emission color in the toluene solution was visually identified as beingbluish.

Thermogravimetry-differential thermal analysis (TG-DTA) was performed onDPAPhAS using a high vacuum differential type differential thermalbalance (type DTA2410SA, manufactured by Bruker AXS K. K.). Themeasurement performed under atmospheric air demonstrated that the 5%weight loss temperature was 434° C., which means that the DPAPhAS hasgood heat resistance. The measurement was performed

Embodiment 5

In this embodiment, a method for manufacturing a light-emitting elementin which(E)-4-{N-[4-(9H-carbazol-9-yl)phenyl]-N-phenyl}amino-4′-(9H-carbazol-9-yl)stilbene(YGACzS) prepared by the synthetic method described in Embodiment 1 isused for a part (a dopant) of a light-emitting layer is described.

First, a first electrode was formed over a substrate. In thisembodiment, a glass substrate was used as the substrate. As a materialfor the first electrode, ITSO (indium tin oxide including silicon oxidewhich was obtained by a sputtering method using a target in whichsilicon oxide of 2 to 10 weight % was included in ITO) which is atransparent conductive film was used. After the ITSO was formed to havea thickness of 110 nm by a sputtering method, the shape of the firstelectrode was made to be a square of 2 mm×2 mm by etching.

Then, as pretreatment for forming the light-emitting element over thefirst electrode, a surface of the substrate was washed with a porousresin (typically made of PVA (polyvinyl alcohol), nylon, or the like),and after that, heat treatment was performed at 200° C. for 1 hour underatmospheric air and UV ozone treatment was performed for 370 seconds.Further, heat treatment was performed at 170° C. for 30 minutes underreduced pressure.

Subsequently, a layer including a luminescent substance was formed overthe first electrode. The layer including a luminescent substance in thisembodiment had a structure in which a hole injecting layer, a holetransporting layer, a light-emitting layer, an electron transportinglayer, and an electron injecting layer were sequentially stacked by avacuum evaporation method.

First, the hole injecting layer was formed over the first electrode. Thehole injecting layer was formed by co-evaporation of4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (abbreviation: NPB) andmolybdenum oxide so that a weight ratio of the NPB to the molybdenumoxide was 4:1. The hole injecting layer was formed to have a thicknessof 50 nm.

Subsequently, the hole transporting layer was formed over the holeinjecting layer. The hole transporting layer was formed by evaporationof NPB. The hole transporting layer was formed to have a thickness of 10nm.

The light-emitting layer was formed over the hole transporting layer.The light-emitting layer was formed by co-evaporation of4,4′-di(N-carbazolyl)biphenyl (abbreviation: CBP) and YGACzS which is astilbene derivative of the present invention so that a weight ratio ofthe CBP to the YGACzS was 1:0.05. The light-emitting layer was formed tohave a thickness of 30 nm.

Subsequently, the electron transporting layer was formed over thelight-emitting layer. The electron transporting layer was formed byevaporation of bathocuproine (abbreviation: BCP). The electrontransporting layer was formed to have a thickness of 10 nm.

Then, the electron injecting layer was formed over the electrontransporting layer. The electron injecting layer was formed byco-evaporation of Alq₃ and lithium so that a weight ratio of the Alq₃ tothe lithium was 1:0.01. The electron injecting layer was formed to havea thickness of 20 nm.

NPB, CBP, BCP, and Alq₃ used for forming the layer including aluminescent substance in this embodiment are shown below.

Then, a second electrode was formed over the electron injecting layer.The second electrode was formed by vacuum evaporation of Al. The secondelectrode was formed to have a thickness of 200 nm.

According to the above-described procedure, the light-emitting elementwas manufactured. It is to be noted that the light-emitting element ispreferably prevented from being exposed to atmospheric air becausedeterioration of the light-emitting element is promoted when it isexposed to atmospheric air. Therefore, in this embodiment, sealing wasperformed using a sealing substrate under a nitrogen atmosphere.

The light-emitting element manufactured as described above was driven byapplying voltage to the light-emitting element, and characteristics ofthe light-emitting element were measured. The light-emitting elementmanufactured in this embodiment is hereinafter referred to as “element1”.

FIG. 14 shows current density-luminance characteristics of the element1, FIG. 15 shows voltage-luminance characteristics thereof, FIG. 16shows luminance-current efficiency characteristics thereof, and FIG. 17shows an emission spectrum thereof. When a voltage of 6.8 V was applied,the element 1 showed a current density of 23.9 mA/cm², a luminance of430 cd/cm², and a current efficiency of 1.8 cd/A. The element 1 had apeak at 442 nm, and chromaticity coordinates in a CIE colorimetricsystem were (x, y)=(0.15, 0.09). From these results, it can be seen thatthe element 1 shows blue emission which substantially conforms to theNTSC standard and is extremely excellent in color purity.

Embodiment 6

In this embodiment, a method for manufacturing a light-emitting elementin which(E)-4-{N-[4-(9H-carbazol-9-yl)phenyl]-N-phenyl}amino-4′-(9H-carbazol-9-yl)stilbene(YGACzS) prepared by the synthetic method described in Embodiment 1 isused for a light-emitting layer is described. The light-emitting elementto be described in this embodiment is manufactured so that it has thesame structure as the light-emitting element described in Embodiment 5,except for the light-emitting layer. Therefore, description of a methodfor manufacturing and structure is omitted except for that of thelight-emitting layer.

The light-emitting layer in this embodiment was formed by evaporation ofYGACzS which is a stilbene derivative of the present invention. Thelight-emitting layer was formed to have a thickness of 30 nm. That is,the light-emitting layer in this embodiment differs from thelight-emitting layer in Embodiment 3 in that only YGACzS which is astilbene derivative of the present invention is used for thelight-emitting layer in this embodiment, whereas YGACzS which is astilbene derivative of the present invention is used as a guestsubstance (a dopant) of the light-emitting layer in Embodiment 3.

The light-emitting element was manufactured by the above-describedmethod. It is to be noted that the light-emitting element is preferablyprevented from being exposed to atmospheric air because deterioration ofthe light-emitting element is promoted when it is exposed to atmosphericair. Therefore, in this embodiment, sealing was performed using asealing substrate under a nitrogen atmosphere.

The light-emitting element manufactured as described above was driven byapplying voltage to the light-emitting element, and characteristics ofthe light-emitting element were measured. The light-emitting elementmanufactured in this embodiment is hereinafter referred to as “element2”.

FIG. 18 shows current density-luminance characteristics of the element2, FIG. 19 shows voltage-luminance characteristics thereof, FIG. 20shows luminance-current efficiency characteristics thereof, and FIG. 21shows emission spectrum thereof. When a voltage of 5.4 V was applied,the element 2 showed a current density of 40.1 mA/cm², a luminance of680 cd/cm², and a current efficiency of 1.7 cd/A. The element 2 had apeak at 450 nm, and chromaticity coordinates in a CIE colorimetricsystem were (x, y)=(0.16, 0.14). From these results, it can be seen thatthe element 2 manufactured using the light-emitting layer formed usingonly YGACzS also shows blue emission which is excellent in color purity.

Embodiment 7

In this embodiment, a method for manufacturing a light-emitting elementin which(E)-4-{N-[4-(9H-carbazol-9-yl)phenyl]-N-phenyl}amino-4′-diphenylaminostilbene(YGADPhAS) prepared by the synthetic method described in Embodiment 2 isused for a part (a dopant) of a light-emitting layer is described.

The light-emitting element described in this embodiment is manufacturedso that the structure is the same as that of the light-emitting elementdescribed in Embodiment 5, except for the light-emitting layer.Therefore, description of a method for manufacturing and structure isomitted, except for that of the light-emitting layer.

The light-emitting layer in this embodiment was formed by co-evaporationof 4,4′-di(N-carbazolyl)biphenyl (abbreviation: CBP) and YGADPhAS, whichis a stilbene derivative of the present invention, so that a weightratio of the CBP and the YGADPhAS was 1:0.05. The light-emitting layerwas formed to have a thickness of 30 nm. That is, the light-emittinglayer in this embodiment differs from the light-emitting layer inEmbodiment 5 in that the YGADPhAS is used as a guest substance of thelight-emitting layer in this embodiment, whereas the YGACzS is used as aguest substance of the light-emitting layer in Embodiment 5.

The light-emitting element was manufactured by the above-describedmethod. It is to be noted that the light-emitting element is preferablyprevented from being exposed to atmospheric air because deterioration ofthe light-emitting element is promoted when it is exposed to atmosphericair. Therefore, in this embodiment, sealing was performed using asealing substrate under a nitrogen atmosphere.

The light-emitting element manufactured as described above was driven byapplying voltage to the light-emitting element, and characteristics ofthe light-emitting element were measured. The light-emitting elementmanufactured in this embodiment is hereinafter referred to as “element3”.

FIG. 22 shows current density-luminance characteristics of the element3, FIG. 23 shows voltage-luminance characteristics thereof, FIG. 24shows luminance-current efficiency characteristics thereof, and FIG. 25shows an emission spectrum thereof. When a voltage of 6.2 V was applied,the element 3 showed a current density of 20.1 mA/cm², a luminance of560 cd/cm², and a current efficiency of 2.8 cd/A. The element 3 had apeak at 445 nm, and chromaticity coordinates in a CIE colorimetricsystem were (x, y)=(0.15, 0.13). From these results, it can be seen thatthe element 3 also shows blue emission which is excellent in colorpurity.

This application is based on Japanese Patent Application serial No.2006-270118 filed in Japan Patent Office on Sep. 29, 2006, the entirecontents of which are hereby incorporated by reference.

What is claimed is:
 1. An organic compound represented by a generalformula (2):

wherein α represents a carbazolyl group or a diarylamino group, whereinAr²¹ represents an aryl group having 6 to 25 carbon atoms, wherein Czrepresents a carbazolyl group, and wherein the diarylamino group has twoaryl groups each independently having 6 to 25 carbon atoms.
 2. Theorganic compound according to claim 1, wherein α is represented by thefollowing general formula:

wherein R⁶¹ and R⁶² each independently represents any one of a hydrogenatom, an alkyl group having 1 to 4 carbon atoms, and an aryl grouphaving 6 to 25 carbon atoms.
 3. The organic compound according to claim1, wherein Cz is represented by the following general formula:

wherein R³¹ represents any one of a hydrogen atom, an alkyl group having1 to 4 carbon atoms, and an aryl group having 6 to 25 carbon atoms, andwherein R³² represents an alkyl group having 1 to 4 carbon atoms or anaryl group having 6 to 25 carbon atoms.
 4. The organic compoundaccording to claim 1, wherein Ar²¹ is represented by any one of thefollowing structural formulae (26-1) to (26-9):


5. The organic compound according to claim 1, wherein the diarylaminogroup is represented by the following general formula:

wherein Ar¹ and Ar² each independently have an aryl group having 6 to 25carbon atoms.
 6. A light-emitting element comprising: a first electrode;a layer comprising the organic compound according to claim 1, whereinthe layer is provided over the first electrode; and a second electrodeover the layer.
 7. A display device comprising a display portioncomprising the light-emitting element according to claim 6.